Intel Fortran Language Reference

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Copyright 2003-2004 Intel Corporation.Portions Copyright 2001 Hewlett-Packard Development Company, L.P. ii

ContentsAbout This ManualProduct Website and Support .................................................................. xxviRelated Publications................................................................................. xxviiConventions .............................................................................................. xxx

Platform Labels.................................................................................... xxxii

Chapter 1 OverviewLanguage Standards Conformance .......................................................... 1-2Language Compatibility............................................................................. 1-2Fortran 2003 Features............................................................................... 1-2

Improved Features................................................................................ 1-3Fortran 95 Features................................................................................... 1-3

New Features ....................................................................................... 1-3Improved Features................................................................................ 1-4

Fortran 90 Features................................................................................... 1-5New Features ....................................................................................... 1-5Improved Features................................................................................ 1-7

Chapter 2 Program Structure, Characters, and Source FormsProgram Structure ..................................................................................... 2-1

Statements ........................................................................................... 2-2Names .................................................................................................. 2-4

Character Sets .......................................................................................... 2-5Source Forms............................................................................................ 2-6

Free Source Form................................................................................. 2-9iii

Intel Fortran Language ReferenceFixed and Tab Source Forms.............................................................. 2-11Fixed-Format Lines ........................................................................ 2-13Tab-Format Lines ........................................................................... 2-13

Source Code Useable for All Source Forms ....................................... 2-15

Chapter 3 Data Types, Constants, and VariablesIntrinsic Data Types ................................................................................... 3-2

Integer Data Types................................................................................ 3-4Real Data Types.................................................................................... 3-6

General Rules for Real Constants.................................................... 3-7REAL(4) Constants .......................................................................... 3-8REAL(8) or DOUBLE PRECISION Constants ................................. 3-9REAL(16) Constants ...................................................................... 3-10

Complex Data Types........................................................................... 3-10General Rules for Complex Constants........................................... 3-11COMPLEX(4) Constants ................................................................ 3-11COMPLEX(8) or DOUBLE COMPLEX Constants ......................... 3-12COMPLEX(16) Constants .............................................................. 3-13

Logical Data Types.............................................................................. 3-14Character Data Type........................................................................... 3-14

C Strings in Character Constants................................................... 3-16 Character Substrings .................................................................... 3-17

Derived Data Types ................................................................................. 3-19Derived-Type Definition....................................................................... 3-20Default Initialization............................................................................. 3-22Structure Components........................................................................ 3-23Structure Constructors........................................................................ 3-26

Binary, Octal, Hexadecimal, and Hollerith Constants .............................. 3-28Binary Constants ................................................................................ 3-28Octal Constants .................................................................................. 3-29Hexadecimal Constants ...................................................................... 3-29Hollerith Constants ............................................................................. 3-30Determining the Data Type of Nondecimal Constants ........................ 3-31

Variables.................................................................................................. 3-33iv

ContentsData Types of Scalar Variables ........................................................... 3-34Specification of Data Type.............................................................. 3-34Implicit Typing Rules....................................................................... 3-35

Arrays.................................................................................................. 3-35Whole Arrays .................................................................................. 3-38Array Elements ............................................................................... 3-38Array Sections ................................................................................ 3-41Array Constructors.......................................................................... 3-44

Chapter 4 Expressions and Assignment StatementsExpressions ............................................................................................... 4-1

Numeric Expressions ............................................................................ 4-2Using Parentheses in Numeric Expressions .................................... 4-4Data Type of Numeric Expressions .................................................. 4-5

Character Expressions.......................................................................... 4-6Relational Expressions.......................................................................... 4-7Logical Expressions .............................................................................. 4-8

Data Types Resulting from Logical Operations ................................ 4-9Evaluation of Logical Expressions.................................................... 4-9

Defined Operations ............................................................................. 4-10Summary of Operator Precedence ..................................................... 4-11Initialization and Specification Expressions ........................................ 4-11

Initialization Expressions ................................................................ 4-12Specification Expressions .............................................................. 4-13

Assignment Statements........................................................................... 4-15Intrinsic Assignments .......................................................................... 4-16

Numeric Assignment Statements ................................................... 4-17Logical Assignment Statements ..................................................... 4-18Character Assignment Statements................................................. 4-18Derived-Type Assignment Statements ........................................... 4-19Array Assignment Statements ........................................................ 4-20

Defined Assignments .......................................................................... 4-21Pointer Assignments ........................................................................... 4-22WHERE Statement and Construct ...................................................... 4-23v

Intel Fortran Language ReferenceFORALL Statement and Construct ..................................................... 4-26

Chapter 5 Specification StatementsType Declaration Statements..................................................................... 5-2

Declaration Statements for Noncharacter Types................................... 5-6Declaration Statements for Character Types ........................................ 5-8Declaration Statements for Derived Types.......................................... 5-10Declaration Statements for Arrays ...................................................... 5-10

Explicit-Shape Specifications ......................................................... 5-11Assumed-Shape Specifications ..................................................... 5-14Assumed-Size Specifications......................................................... 5-15Deferred-Shape Specifications ...................................................... 5-16

ALLOCATABLE Attribute and Statement ................................................. 5-17AUTOMATIC and STATIC Attributes and Statements.............................. 5-18COMMON Statement .............................................................................. 5-21DATA Statement....................................................................................... 5-24DIMENSION Attribute and Statement ..................................................... 5-27EQUIVALENCE Statement ...................................................................... 5-29

Making Arrays Equivalent ................................................................... 5-31Making Substrings Equivalent............................................................. 5-33EQUIVALENCE and COMMON Interaction ........................................ 5-35

EXTERNAL Attribute and Statement....................................................... 5-38IMPLICIT Statement ................................................................................ 5-39INTENT Attribute and Statement............................................................. 5-41INTRINSIC Attribute and Statement........................................................ 5-43NAMELIST Statement ............................................................................. 5-45OPTIONAL Attribute and Statement........................................................ 5-46PARAMETER Attribute and Statement.................................................... 5-48POINTER Attribute and Statement.......................................................... 5-50PRIVATE and PUBLIC Attributes and Statements................................... 5-51SAVE Attribute and Statement ................................................................ 5-54TARGET Attribute and Statement............................................................ 5-55VOLATILE Attribute and Statement ......................................................... 5-57vi

ContentsChapter 6 Dynamic AllocationALLOCATE Statement ............................................................................... 6-2

Allocation of Allocatable Arrays............................................................. 6-3Allocation of Pointer Targets.................................................................. 6-4

DEALLOCATE Statement .......................................................................... 6-5Deallocation of Allocatable Arrays......................................................... 6-6Deallocation of Pointer Targets ............................................................. 6-7

NULLIFY Statement................................................................................... 6-8

Chapter 7 Execution ControlBranch Statements .................................................................................... 7-2

Unconditional GO TO Statement .......................................................... 7-2Computed GO TO Statement................................................................ 7-3The ASSIGN and Assigned GO TO Statements................................... 7-4

ASSIGN Statement .......................................................................... 7-4Assigned GO TO Statement............................................................. 7-5

Arithmetic IF Statement ........................................................................ 7-6CALL Statement ........................................................................................ 7-7CASE Constructs....................................................................................... 7-9CONTINUE Statement............................................................................. 7-14DO Constructs ......................................................................................... 7-14

Forms for DO Constructs .................................................................... 7-15Execution of DO Constructs................................................................ 7-17

Iteration Loop Control ..................................................................... 7-17Nested DO Constructs ................................................................... 7-19Extended Range............................................................................. 7-21

DO WHILE Statement ......................................................................... 7-23CYCLE Statement............................................................................... 7-24EXIT Statement................................................................................... 7-24

END Statement........................................................................................ 7-25IF Construct and Statement..................................................................... 7-26

IF Construct ........................................................................................ 7-26IF Statement........................................................................................ 7-31

PAUSE Statement.................................................................................... 7-32vii

Intel Fortran Language ReferenceRETURN Statement ................................................................................ 7-33STOP Statement...................................................................................... 7-35

Chapter 8 Program Units and Procedures Main Program ............................................................................................ 8-2Modules and Module Procedures.............................................................. 8-4

Module References............................................................................... 8-7USE Statement ..................................................................................... 8-8

Block Data Program Units ....................................................................... 8-10Functions, Subroutines, and Statement Functions.................................. 8-12

General Rules for Function and Subroutine Subprograms ................. 8-13Recursive Procedures.................................................................... 8-13Pure Procedures ............................................................................ 8-14Elemental Procedures.................................................................... 8-17

Functions ............................................................................................ 8-18RESULT Keyword........................................................................... 8-23Function References ...................................................................... 8-23

Subroutines......................................................................................... 8-24Statement Functions........................................................................... 8-27

External Procedures................................................................................ 8-28Internal Procedures ................................................................................. 8-29Argument Association.............................................................................. 8-30

Optional Arguments ............................................................................ 8-32Array Arguments ................................................................................. 8-33Pointer Arguments .............................................................................. 8-34Assumed-Length Character Arguments.............................................. 8-35Character Constant and Hollerith Arguments ..................................... 8-36Alternate Return Arguments ............................................................... 8-37Dummy Procedure Arguments............................................................ 8-37References to Generic Procedures..................................................... 8-38

References to Generic Intrinsic Functions ..................................... 8-39References to Elemental Intrinsic Procedures ............................... 8-42

References to Non-Fortran Procedures.............................................. 8-43%REF and %VAL Argument List Functions ................................... 8-43viii

Contents%LOC Function .............................................................................. 8-44Procedure Interfaces................................................................................ 8-45

Determining When Procedures Require Explicit Interfaces ................ 8-46Defining Explicit Interfaces.................................................................. 8-46Defining Generic Names for Procedures ............................................ 8-49Defining Generic Operators ................................................................ 8-50Defining Generic Assignment ............................................................. 8-51

CONTAINS Statement ............................................................................. 8-53ENTRY Statement ................................................................................... 8-53

ENTRY Statements in Function Subprograms.................................... 8-55ENTRY Statements in Subroutine Subprograms ................................ 8-56

Chapter 9 Intrinsic ProceduresArgument Keywords in Intrinsic Procedures .............................................. 9-3Overview of Intrinsic Procedures ............................................................... 9-4

Categories of Intrinsic Functions........................................................... 9-4Intrinsic Subroutines ........................................................................... 9-15Bit Functions ....................................................................................... 9-16

Descriptions of Intrinsic Procedures ........................................................ 9-18ABS..................................................................................................... 9-18ACHAR................................................................................................ 9-19ACOS .................................................................................................. 9-20ACOSD ............................................................................................... 9-20ACOSH ............................................................................................... 9-21ADJUSTL ............................................................................................ 9-21ADJUSTR............................................................................................ 9-22AIMAG................................................................................................. 9-22AINT.................................................................................................... 9-23ALL...................................................................................................... 9-23ALLOCATED ....................................................................................... 9-24ANINT ................................................................................................. 9-25ANY..................................................................................................... 9-25ASIN.................................................................................................... 9-26ASIND ................................................................................................. 9-27ix

Intel Fortran Language ReferenceASINH................................................................................................. 9-27ASSOCIATED ..................................................................................... 9-28ATAN ................................................................................................... 9-29ATAN2 ................................................................................................. 9-30ATAN2D............................................................................................... 9-31ATAND................................................................................................. 9-31ATANH................................................................................................. 9-32BADDRESS ........................................................................................ 9-32BIT_SIZE ............................................................................................ 9-33BTEST ................................................................................................ 9-33CACHESIZE (i64 only)........................................................................ 9-34CEILING ............................................................................................. 9-35CHAR.................................................................................................. 9-35CMPLX ............................................................................................... 9-36CONJG ............................................................................................... 9-37COS .................................................................................................... 9-37COSD ................................................................................................. 9-38COSH ................................................................................................. 9-39COTAN................................................................................................ 9-39COTAND ............................................................................................. 9-40COUNT ............................................................................................... 9-40CPU_TIME.......................................................................................... 9-41CSHIFT............................................................................................... 9-42DATE................................................................................................... 9-43DATE_AND_TIME............................................................................... 9-44DBLE .................................................................................................. 9-46DCMPLX............................................................................................. 9-47DFLOAT .............................................................................................. 9-47DIGITS................................................................................................ 9-48DIM ..................................................................................................... 9-48DNUM ................................................................................................. 9-49DOT_PRODUCT................................................................................. 9-50DPROD............................................................................................... 9-51DREAL................................................................................................ 9-51x

ContentsDSHIFTL ............................................................................................. 9-52DSHIFTR............................................................................................. 9-52EOF..................................................................................................... 9-53EOSHIFT............................................................................................. 9-54EPSILON............................................................................................. 9-56ERF..................................................................................................... 9-56ERFC .................................................................................................. 9-57ERRSNS ............................................................................................. 9-58EXIT .................................................................................................... 9-59EXP..................................................................................................... 9-59EXPONENT ........................................................................................ 9-60FLOOR................................................................................................ 9-60FP_CLASS.......................................................................................... 9-61FRACTION.......................................................................................... 9-61FREE................................................................................................... 9-62GETARG ............................................................................................. 9-62HUGE.................................................................................................. 9-64IACHAR............................................................................................... 9-64IAND.................................................................................................... 9-65IARGC................................................................................................. 9-65IARGPTR ............................................................................................ 9-66IBCHNG .............................................................................................. 9-67IBCLR.................................................................................................. 9-67IBITS ................................................................................................... 9-68IBSET.................................................................................................. 9-69ICHAR................................................................................................. 9-70IDATE .................................................................................................. 9-71IEOR ................................................................................................... 9-71ILEN .................................................................................................... 9-72INDEX ................................................................................................. 9-73INT ...................................................................................................... 9-73INT_PTR_KIND................................................................................... 9-75INUM................................................................................................... 9-76IOR...................................................................................................... 9-76xi

Intel Fortran Language ReferenceISHA ................................................................................................... 9-77ISHC ................................................................................................... 9-78ISHFT ................................................................................................. 9-79ISHFTC............................................................................................... 9-80ISHL.................................................................................................... 9-81ISNAN................................................................................................. 9-82JNUM.................................................................................................. 9-82KIND ................................................................................................... 9-82LBOUND............................................................................................. 9-83LEADZ ................................................................................................ 9-84LEN..................................................................................................... 9-85LEN_TRIM .......................................................................................... 9-85LGE..................................................................................................... 9-86LGT..................................................................................................... 9-87LLE ..................................................................................................... 9-87LLT ...................................................................................................... 9-88LOC .................................................................................................... 9-89LOG .................................................................................................... 9-89LOG10 ................................................................................................ 9-90LOGICAL ............................................................................................ 9-91MALLOC ............................................................................................. 9-91MATMUL ............................................................................................. 9-92MAX .................................................................................................... 9-93MAXEXPONENT ................................................................................ 9-95MAXLOC............................................................................................. 9-95MAXVAL.............................................................................................. 9-97MCLOCK ............................................................................................ 9-98MERGE............................................................................................... 9-98MIN ..................................................................................................... 9-99MINEXPONENT ............................................................................... 9-100MINLOC............................................................................................ 9-100MINVAL............................................................................................. 9-102MM_PREFETCH .............................................................................. 9-103MOD ................................................................................................. 9-105xii

ContentsMODULO .......................................................................................... 9-106MULT_HIGH (i64 only) ..................................................................... 9-106MVBITS............................................................................................. 9-107NARGS ............................................................................................. 9-108NEAREST ......................................................................................... 9-110NINT.................................................................................................. 9-110NOT................................................................................................... 9-111NULL................................................................................................. 9-112PACK................................................................................................. 9-113POPCNT ........................................................................................... 9-114POPPAR............................................................................................ 9-114PRECISION ...................................................................................... 9-114PRESENT ......................................................................................... 9-115PRODUCT ........................................................................................ 9-116QCMPLX........................................................................................... 9-117QEXT ................................................................................................ 9-117QFLOAT ............................................................................................ 9-118QNUM ............................................................................................... 9-119QREAL.............................................................................................. 9-119RADIX ............................................................................................... 9-120RAN................................................................................................... 9-120RANDOM_NUMBER......................................................................... 9-121RANDOM_SEED .............................................................................. 9-122RANDU ............................................................................................. 9-124RANGE ............................................................................................. 9-124REAL................................................................................................. 9-125REPEAT ............................................................................................ 9-126RESHAPE......................................................................................... 9-127RNUM ............................................................................................... 9-128RRSPACING ..................................................................................... 9-128SCALE .............................................................................................. 9-128SCAN ................................................................................................ 9-129SECNDS ........................................................................................... 9-130SELECTED_INT_KIND..................................................................... 9-130xiii

Intel Fortran Language ReferenceSELECTED_REAL_KIND................................................................. 9-131SET_EXPONENT ............................................................................. 9-132SHAPE.............................................................................................. 9-132SHIFTL ............................................................................................. 9-133SHIFTR............................................................................................. 9-133SIGN ................................................................................................. 9-134SIN.................................................................................................... 9-135SIND ................................................................................................. 9-135SINH ................................................................................................. 9-136SIZE.................................................................................................. 9-136SIZEOF............................................................................................. 9-137SPACING .......................................................................................... 9-138SPREAD ........................................................................................... 9-138SQRT................................................................................................ 9-139SUM.................................................................................................. 9-140SYSTEM_CLOCK............................................................................. 9-141TAN ................................................................................................... 9-142TAND ................................................................................................ 9-143TANH ................................................................................................ 9-143TIME ................................................................................................. 9-144TINY.................................................................................................. 9-144TRAILZ ............................................................................................. 9-145TRANSFER ...................................................................................... 9-145TRANSPOSE.................................................................................... 9-146TRIM ................................................................................................. 9-147UBOUND .......................................................................................... 9-147UNPACK ........................................................................................... 9-148VERIFY............................................................................................. 9-149ZEXT................................................................................................. 9-150

Chapter 10 Data Transfer I/O StatementsRecords and Files.................................................................................... 10-1Components of Data Transfer Statements............................................... 10-2

I/O Control List .................................................................................... 10-3xiv

ContentsUnit Specifier .................................................................................. 10-4Format Specifier ............................................................................. 10-5Namelist Specifier .......................................................................... 10-6Record Specifier............................................................................. 10-6I/O Status Specifier ........................................................................ 10-6Branch Specifiers ........................................................................... 10-7Advance Specifier .......................................................................... 10-8Character Count Specifier .............................................................. 10-9

I/O Lists ............................................................................................... 10-9Simple List Items in I/O Lists ........................................................ 10-10implied-DO Lists in I/O Lists ......................................................... 10-12

READ Statements.................................................................................. 10-13Forms for Sequential READ Statements........................................... 10-13

Rules for Formatted Sequential READ Statements...................... 10-15Rules for List-Directed Sequential READ Statements.................. 10-15Rules for Namelist Sequential READ Statements ........................ 10-18Rules for Unformatted Sequential READ Statements .................. 10-23

Forms for Direct-Access READ Statements ..................................... 10-24Rules for Formatted Direct-Access READ Statements ................ 10-25Rules for Unformatted Direct-Access READ Statements ............. 10-26

Forms and Rules for Internal READ Statements .............................. 10-26ACCEPT Statement ............................................................................... 10-28WRITE Statements ................................................................................ 10-29

Forms for Sequential WRITE Statements ......................................... 10-29Rules for Formatted Sequential WRITE Statements .................... 10-30Rules for List-Directed Sequential WRITE Statements ................ 10-31Rules for Namelist Sequential WRITE Statements ...................... 10-33Rules for Unformatted Sequential WRITE Statements................. 10-34

Forms for Direct-Access WRITE Statements.................................... 10-35Rules for Formatted Direct-Access WRITE Statements............... 10-36Rules for Unformatted Direct-Access WRITE Statements ........... 10-36

Forms and Rules for Internal WRITE Statements............................. 10-36PRINT and TYPE Statements ............................................................... 10-38REWRITE Statement............................................................................. 10-39xv

Intel Fortran Language ReferenceChapter 11 I/O FormattingFormat Specifications .............................................................................. 11-2Data Edit Descriptors............................................................................... 11-6

Forms for Data Edit Descriptors.......................................................... 11-6General Rules for Numeric Editing ..................................................... 11-8Integer Editing..................................................................................... 11-9

I Editing .......................................................................................... 11-9B Editing....................................................................................... 11-11O Editing ...................................................................................... 11-12Z Editing ....................................................................................... 11-13

Real and Complex Editing ................................................................ 11-14F Editing ....................................................................................... 11-15E and D Editing ............................................................................ 11-16EN Editing .................................................................................... 11-19ES Editing .................................................................................... 11-20G Editing ...................................................................................... 11-22Complex Editing ........................................................................... 11-24

Logical Editing (L) ............................................................................. 11-25Character Editing (A) ........................................................................ 11-26Default Widths for Data Edit Descriptors .......................................... 11-28Terminating Short Fields of Input Data ............................................. 11-29

Control Edit Descriptors......................................................................... 11-30Forms for Control Edit Descriptors.................................................... 11-30Positional Editing .............................................................................. 11-31

T Editing ....................................................................................... 11-31TL Editing ..................................................................................... 11-32TR Editing .................................................................................... 11-32X Editing....................................................................................... 11-32

Sign Editing....................................................................................... 11-33SP Editing .................................................................................... 11-33SS Editing .................................................................................... 11-33S Editing....................................................................................... 11-33

Blank Editing..................................................................................... 11-33BN Editing .................................................................................... 11-34xvi

ContentsBZ Editing..................................................................................... 11-34Scale Factor Editing (P) .................................................................... 11-34Slash Editing (/)................................................................................. 11-36Colon Editing (:) ................................................................................ 11-37Dollar Sign ($) and Backslash (\) Editing .......................................... 11-37Character Count Editing (Q).............................................................. 11-38

Character String Edit Descriptors .......................................................... 11-38Character Constant Editing ............................................................... 11-39H Editing............................................................................................ 11-39

Nested and Group Repeat Specifications.............................................. 11-40Variable Format Expressions ................................................................. 11-41Printing of Formatted Records............................................................... 11-42Interaction Between Format Specifications and I/O Lists ...................... 11-43

Chapter 12 File Operation I/O StatementsBACKSPACE Statement .......................................................................... 12-2CLOSE Statement ................................................................................... 12-3DELETE Statement ................................................................................. 12-4ENDFILE Statement ................................................................................ 12-5INQUIRE Statement ................................................................................ 12-7

ACCESS Specifier .............................................................................. 12-8ACTION Specifier................................................................................ 12-9BINARY Specifier (W*32, W*64) ......................................................... 12-9BLANK Specifier ................................................................................. 12-9BLOCKSIZE Specifier ....................................................................... 12-10BUFFERED Specifier........................................................................ 12-10CARRIAGECONTROL Specifier ....................................................... 12-10CONVERT Specifier.......................................................................... 12-11DELIM Specifier ................................................................................ 12-12DIRECT Specifier.............................................................................. 12-12EXIST Specifier................................................................................. 12-12FORM Specifier................................................................................. 12-13FORMATTED Specifier ..................................................................... 12-13IOFOCUS Specifier (W*32, W*64).................................................... 12-13xvii

Intel Fortran Language ReferenceMODE Specifier ................................................................................ 12-14NAME Specifier ................................................................................ 12-14NAMED Specifier .............................................................................. 12-14NEXTREC Specifier.......................................................................... 12-15NUMBER Specifier ........................................................................... 12-15OPENED Specifier............................................................................ 12-15ORGANIZATION Specifier ................................................................ 12-16PAD Specifier .................................................................................... 12-16POSITION Specifier.......................................................................... 12-16READ Specifier ................................................................................. 12-17READWRITE Specifier ..................................................................... 12-17RECL Specifier ................................................................................. 12-17RECORDTYPE Specifier .................................................................. 12-18SEQUENTIAL Specifier .................................................................... 12-18SHARE Specifier (W*32, W*64) ....................................................... 12-19UNFORMATTED Specifier................................................................ 12-19WRITE Specifier ............................................................................... 12-19

OPEN Statement ................................................................................... 12-20ACCESS Specifier ............................................................................ 12-24ACTION Specifier ............................................................................. 12-25ASSOCIATEVARIABLE Specifier ..................................................... 12-25BLANK Specifier ............................................................................... 12-26BLOCKSIZE Specifier....................................................................... 12-26BUFFERCOUNT Specifier................................................................ 12-26BUFFERED Specifier........................................................................ 12-27CARRIAGECONTROL Specifier....................................................... 12-28CONVERT Specifier ......................................................................... 12-28DEFAULTFILE Specifier.................................................................... 12-30DELIM Specifier ................................................................................ 12-30DISPOSE Specifier ........................................................................... 12-31FILE Specifier ................................................................................... 12-32FORM Specifier ................................................................................ 12-32IOFOCUS Specifier (W*32, W*64) ................................................... 12-33MAXREC Specifier ........................................................................... 12-33xviii

ContentsMODE Specifier ................................................................................ 12-33NAME Specifier................................................................................. 12-33ORGANIZATION Specifier ................................................................ 12-34PAD Specifier .................................................................................... 12-34POSITION Specifier .......................................................................... 12-35READONLY Specifier........................................................................ 12-35RECL Specifier.................................................................................. 12-36RECORDSIZE Specifier.................................................................... 12-37RECORDTYPE Specifier .................................................................. 12-37SHARE Specifier (W*32, W*64)........................................................ 12-38SHARED Specifier ............................................................................ 12-39STATUS Specifier.............................................................................. 12-39TITLE Specifier (W*32, W*64) .......................................................... 12-40TYPE Specifier.................................................................................. 12-40USEROPEN Specifier ....................................................................... 12-40

REWIND Statement............................................................................... 12-41UNLOCK Statement .............................................................................. 12-42

Chapter 13 Compilation Control StatementsINCLUDE Statement................................................................................ 13-1OPTIONS Statement ............................................................................... 13-3

Chapter 14 Directive Enhanced CompilationSyntax Rules for Compiler Directives ...................................................... 14-1General Compiler Directives .................................................................... 14-2

Rules for General Directives that Affect DO Loops ............................. 14-4ALIAS Directive ................................................................................... 14-5ATTRIBUTES Directive ....................................................................... 14-5

ATTRIBUTES ALIAS ...................................................................... 14-8ATTRIBUTES ALIGN...................................................................... 14-9ATTRIBUTES ALLOCATABLE........................................................ 14-9ATTRIBUTES ALLOW_NULL......................................................... 14-9ATTRIBUTES ARRAY_VISUALIZER............................................ 14-10ATTRIBUTES C and STDCALL.................................................... 14-10xix

Intel Fortran Language ReferenceATTRIBUTES DECORATE........................................................... 14-12ATTRIBUTES DEFAULT............................................................... 14-12ATTRIBUTES DLLEXPORT and DLLIMPORT (W*32, W*64) ..... 14-13ATTRIBUTES EXTERN................................................................ 14-13ATTRIBUTES IGNORE_LOC....................................................... 14-13ATTRIBUTES INLINE, NOINLINE, and FORCEDINLINE............ 14-14ATTRIBUTES NO_ARG_CHECK ................................................ 14-14ATTRIBUTES NOMIXED_STR_LEN_ARG ................................. 14-15ATTRIBUTES REFERENCE and VALUE..................................... 14-15ATTRIBUTES VARYING............................................................... 14-16

DECLARE and NODECLARE Directives.......................................... 14-16DEFINE and UNDEFINE Directives.................................................. 14-16DISTRIBUTE POINT Directive.......................................................... 14-18FIXEDFORMLINESIZE Directive...................................................... 14-19FREEFORM and NOFREEFORM Directives ................................... 14-20IDENT Directive ................................................................................ 14-20IF and IF DEFINED Directives .......................................................... 14-20INTEGER Directive ........................................................................... 14-22IVDEP Directive ................................................................................ 14-23LOOP COUNT Directive ................................................................... 14-25MESSAGE Directive ......................................................................... 14-26OBJCOMMENT Directive ................................................................. 14-26OPTIONS Directive........................................................................... 14-27PACK Directive.................................................................................. 14-30PARALLEL and NOPARALLEL Directives ........................................ 14-31PREFETCH and NOPREFETCH Directives ..................................... 14-32PSECT Directive ............................................................................... 14-33REAL Directive.................................................................................. 14-35STRICT and NOSTRICT Directives................................................. 14-36SWP and NOSWP Directives (i64 only)............................................ 14-38TITLE and SUBTITLE Directives ...................................................... 14-39UNROLL and NOUNROLL Directives............................................... 14-39VECTOR ALIGNED and VECTOR UNALIGNED Directives (i32 only) .......

14-40xx

ContentsVECTOR ALWAYS and NOVECTOR Directives (i32 only)................ 14-41VECTOR NONTEMPORAL Directive (i32 only)................................ 14-42

OpenMP* Fortran Compiler Directives................................................... 14-42Data Scope Attribute Clauses ........................................................... 14-44

COPYIN Clause ........................................................................... 14-45COPYPRIVATE Clause ................................................................ 14-45DEFAULT Clause.......................................................................... 14-46FIRSTPRIVATE Clause ................................................................ 14-46LASTPRIVATE Clause.................................................................. 14-47PRIVATE Clause........................................................................... 14-47REDUCTION Clause.................................................................... 14-48SHARED Clause .......................................................................... 14-49

Conditional Compilation Rules .......................................................... 14-50Nesting and Binding Rules............................................................... 14-51ATOMIC Directive.............................................................................. 14-53BARRIER Directive ........................................................................... 14-54CRITICAL Directive........................................................................... 14-55DO Directive...................................................................................... 14-56FLUSH Directive ............................................................................... 14-59MASTER Directive ............................................................................ 14-61ORDERED Directive ......................................................................... 14-61PARALLEL Directive ......................................................................... 14-63PARALLEL DO Directive .................................................................. 14-65PARALLEL SECTIONS Directive ..................................................... 14-66SECTIONS Directive........................................................................ 14-67SINGLE Directive ............................................................................. 14-69THREADPRIVATE Directive............................................................. 14-70

Chapter 15 Scope and AssociationScope....................................................................................................... 15-1Unambiguous Generic Procedure References ........................................ 15-4Resolving Procedure References ............................................................ 15-5

References to Generic Names............................................................ 15-5References to Specific Names............................................................ 15-7xxi

Intel Fortran Language ReferenceReferences to Nonestablished Names ............................................... 15-8Association .............................................................................................. 15-9

Name Association............................................................................. 15-10Argument Association .................................................................. 15-10Use and Host Association ............................................................ 15-11

Pointer Association ........................................................................... 15-12Storage Association.......................................................................... 15-13

Storage Units and Storage Sequence.......................................... 15-13Array Association ......................................................................... 15-15

Appendix A Deleted and Obsolescent Language FeaturesDeleted Language Features in Fortran 95................................................. A-1Obsolescent Language Features in Fortran 95 ......................................... A-2Obsolescent Language Features in Fortran 90 ......................................... A-3

Appendix B Additional Language FeaturesDEFINE FILE Statement ........................................................................... B-1ENCODE and DECODE Statements......................................................... B-3FIND Statement......................................................................................... B-5INTERFACE TO Statement ....................................................................... B-5FORTRAN-66 Interpretation of the EXTERNAL Statement ...................... B-6Alternative Syntax for the PARAMETER Statement .................................. B-8VIRTUAL Statement .................................................................................. B-9Alternative Syntax for Octal and Hexadecimal Constants ....................... B-10Alternative Syntax for a Record Specifier ................................................ B-10Alternative Syntax for the DELETE Statement ........................................ B-10Alternative Form for Namelist External Records ..................................... B-11Integer POINTER Statement .................................................................. B-12Record Structures.................................................................................... B-13

Structure Declarations ........................................................................ B-14Type Declarations........................................................................... B-18Substructure Declarations............................................................. B-18Union Declarations......................................................................... B-19

RECORD Statement........................................................................... B-21xxii

ContentsReferences to Record Fields.............................................................. B-22Aggregate Assignment....................................................................... B-24

Appendix C The ASCII Character Set for Linux SystemsThe ASCII Character Set (L*X) ................................................................. C-1

Appendix D Data Representation ModelsModel for Integer Data .............................................................................. D-2Model for Real Data .................................................................................. D-3Model for Bit Data ..................................................................................... D-4

Appendix E Run-Time Library RoutinesModule Routines....................................................................................... E-1

Portability Routines .............................................................................. E-2National Language Support Routines (W*32, W*64) ........................... E-8POSIX* Routines................................................................................ E-10QuickWin Routines (W*32, W*64)...................................................... E-15Graphics Routines (W*32, W*64)....................................................... E-16Dialog Routines (W*32)...................................................................... E-21Miscellaneous Run-Time Routines .................................................... E-22COM Routines (W*32) ....................................................................... E-23AUTO Routines (W*32) ...................................................................... E-24

OpenMP* Fortran Routines .................................................................... E-25

Appendix F Summary of Language ExtensionsSource Forms ............................................................................................ F-1Names ....................................................................................................... F-1Character Sets........................................................................................... F-1Intrinsic Data Types ................................................................................... F-2Constants................................................................................................... F-2Expressions and Assignment .................................................................... F-2Specification Statements ........................................................................... F-2Execution Control....................................................................................... F-3Compilation Control Statements ................................................................ F-3Built-In Functions ....................................................................................... F-3xxiii

Intel Fortran Language ReferenceI/O Statements........................................................................................... F-3I/O Formatting............................................................................................ F-3File Operation Statements......................................................................... F-4Compiler Directives ................................................................................... F-5Intrinsic Procedures................................................................................... F-7Additional Language Features................................................................... F-9Run-Time Library Routines...................................................................... F-10

Glossary

Indexxxiv

About This Manual

This manual contains the complete description of the Intel Fortran programming language, which includes Fortran 95, Fortran 90, and some Fortran 2000 language features. It contains information on language syntax and semantics, on adherence to various Fortran standards, and on extensions to those standards.It applies to the following: Intel Fortran for Linux* on IA-32 systems Intel Fortran for Linux on Intel Itanium systems Intel Visual Fortran on IA-32 and Intel Itanium systems For details on the features of the compilers and how to improve the run-time performance of Fortran programs, see your users guide.This manual is intended for experienced applications programmers who have a basic understanding of Fortran concepts and the Fortran 95/90 language, and are using Intel Fortran in either a single-platform or multiplatform environment.Some familiarity with parallel programming concepts and your operating system is helpful. This manual is not a Fortran or programming tutorial.This manual is organized as follows: Chapter 1, Overview, describes language standards, language compatibility, and Fortran

95/90 features. Chapter 2, Program Structure, Characters, and Source Forms, describes program structure,

the Fortran 95/90 character set, and source forms. Chapter 3, Data Types, Constants, and Variables, describes intrinsic and derived data types,

constants, variables (scalars and arrays), and substrings. Chapter 4, Expressions and Assignment Statements, describes Fortran expressions and

assignment statements, which are used to define or redefine variables. Chapter 5, Specification Statements, describes specification statements, which are used to

declare the attributes of data objects.xxv

Intel Fortran Language Reference Chapter 6, Dynamic Allocation, describes statements used in dynamic allocation. Chapter 7, Execution Control, describes constructs and statements that can transfer control

within a program. Chapter 8, Program Units and Procedures, describes program units (including modules),

subroutines and functions, and procedure interfaces. Chapter 9, Intrinsic Procedures, summarizes all intrinsic procedures. Chapter 10, Data Transfer I/O Statements,describes data transfer input/output (I/O)

statements. Chapter 11, I/O Formatting, describes the rules for I/O formatting. Chapter 12, File Operation I/O Statements, describes auxiliary I/O statements you can use

to perform file operations. Chapter 13, Compilation Control Statements, describes compilation control statements. Chapter 14, Directive Enhanced Compilation, describes general and parallel compiler

directives. Chapter 15, Scope and Association, describes scope and association. Appendix A, Deleted and Obsolescent Language Features, describes deleted features in

Fortran 95 and obsolescent language features in Fortran 95 and Fortran 90. Appendix B, Additional Language Features, describes some statements and language

features supported for programs written in older versions of Fortran. Appendix C, The ASCII Character Set for Linux Systems, describes the ASCII character

set available on Linux* systems. For information on character sets available on Windows* systems, see the online documentation for those systems.

Appendix D, Data Representation Models, describes data representation models for numeric intrinsic functions.

Appendix E, Run-Time Library Routines, summarizes the many run-time library routines. Appendix F, Summary of Language Extensions, summarizes Intel Fortran extensions to the

Fortran 95 Standard. The Glossary contains abbreviated definitions of some commonly used terms in this manual.

Product Website and SupportFor the latest product information, visit the Intel web site:

http://developer.intel.com/software/products/ At this site, you will find comprehensive product information, including: Links to each product, where you will find technical information such as white papers and

articlesxxvi

http://developer.intel.com/software/products/

About This Manual Links to user forums Links to news and eventsTo find technical support information, to register your product, or to contact Intel, please visit:

http://www.intel.com/software/products/support

Related Publications

Tutorial information on Fortran 95 and Fortran 90

The following commercially published documents provide reference or tutorial information on Fortran 95 and Fortran 90: Compaq Visual Fortran by N. Lawrence; published by Digital Press*

(Butterworth-Heinemann), ISBN: 1-55558-249-4. Digital Visual Fortran Programmers Guide by M. Etzel and K. Dickinson; published by

Digital Press* (Butterworth-Heinemann), ISBN: 1-55558-218-4. Fortran 90 Explained by M. Metcalf and J. Reid; published by Oxford University Press,

ISBN 0-19-853772-7. Fortran 90/95 Explained by M. Metcalf and J. Reid; published by Oxford University Press,

ISBN 0-19-851888-9. Fortran 90/95 for Scientists and Engineers by S. Chapman; published by McGraw-Hill,

ISBN 0-07-011938-4. Fortran 90 Handbook by J. Adams, W. Brainerd, J. Martin, B. Smith, and J. Wagener;

published by Intertext Publications (McGraw-Hill), ISBN 0-07-000406-4. Fortran 90 Programming by T. Ellis, I. Philips, and T. Lahey; published by Addison-Wesley,

ISBN 0201-54446-6. Introduction to Fortran 90/95 by Stephen J. Chapman; published by WCB McGraw-Hill,

ISBN 0-07-011969-4. Programmers Guide to Fortran 90, Second Edition by W. Brainerd, C. Goldberg, and J.

Adams; published by Unicomp, ISBN 0-07-000248-7.Intel does not endorse these books or recommend them over other books on the same subjects.

Standard and Specification Documents

The following copyrighted standard and specification documents provide descriptions of many of the features found in Intel Fortran: American National Standard Programming Language FORTRAN, ANSI X3.9-1978xxvii

http://www.intel.com/software/products/support

Intel Fortran Language Reference American National Standard Programming Language Fortran 90, ANSI X3.198-1992 This Standard is equivalent to: International Standards Organization Programming Language Fortran, ISO/IEC 1539:1991 (E).

American National Standard Programming Language Fortran 95, ANSI X3J3/96-007 This Standard is equivalent to: International Standards Organization Programming Language Fortran, ISO/IEC 1539-1:1997 (E).

High Performance Fortran Language Specification, Version 1.1, Technical Report CRPC-TR-92225

OpenMP Fortran Application Program Interface, Version 1.1, November 1999 OpenMP Fortran Application Program Interface, Version 2.0, November 2000

Associated Intel Documents

The following Intel documents provide additional information about the Intel Fortran Compiler, Intel architecture, Intel processors, or tools: Intel Fortran Language Reference Intel Fortran Libraries Reference Intel Visual Fortran Compiler for Windows* Systems Installing and Getting Started Intel Array Visualizer online help reference Intel Array Viewer online help reference Using the Intel License Manager for FLEXlm* Intel C++ Compiler User's Guide VTune Performance Analyzer online help Enhanced Debugger online help Intel Architecture Software Developer's Manual, Volume 1: Basic Architecture, Intel

Corporation, doc. number 243190 Intel Architecture Software Developer's Manual, Volume 2: Instruction Set Reference

Manual, Intel Corporation, doc. number 243191 Intel Architecture Software Developer's Manual, Volume 3: System Programming, Intel

Corporation, doc. number 243192 Pentium Processor Family Developer's Manual Intel Processor Identification with the CPUID Instruction, Intel Corporation, doc. number

241618 Intel Itanium Architecture Manuals Intel Itanium Architecture Software Conventions & Runtime Architecture Guide Intel Itanium Assembler User's Guide Intel Itanium Architecture Assembly Language Reference Guide xxviii

About This ManualMost Intel documents can be found at the Intel web site: http://developer.intel.com/software/products/

Optimization and Vectorization Terminology and Technology

The following documents provide details on basic optimization and vectorization terminology and technology: Intel Architecture Optimization Reference Manual Dependence Analysis, Utpal Banerjee (A Book Series on Loop Transformations for

Restructuring Compilers). Kluwer Academic Publishers. 1997. The Structure of Computers and Computation: Volume I, David J. Kuck. John Wiley and

Sons, New York, 1978. Loop Transformations for Restructuring Compilers: The Foundations, Utpal Banerjee (A

Book Series on Loop Transformations for Restructuring Compilers). Kluwer Academic Publishers. 1993.

Loop parallelization, Utpal Banerjee (A Book Series on Loop Transformations for Restructuring Compilers). Kluwer Academic Publishers. 1994.

High Performance Compilers for Parallel Computers, Michael J. Wolfe. Addison-Wesley, Redwood City. 1996.

Supercompilers for Parallel and Vector Computers, H. Zima. ACM Press, New York, 1990. An Auto-vectorizing Compiler for the Intel Architecture, Aart Bik, Paul Grey, Milind

Girkar, and Xinmin Tian. Submitted for publication Efficient Exploitation of Parallelism on Pentium III and Pentium 4 Processor-Based

Systems, Aart Bik, Milind Girkar, Paul Grey, and Xinmin Tian. The Software Vectorization Handbook. Applying Multimedia Extensions for Maximum

Performance, A.J.C. Bik. Intel Press, June, 2004.

Tutorial information on the Intel Fortran Compiler

The following resources provide tutorial help on the Intel Fortran Compiler:For additional training on the Intel Fortran Compiler, choose a course in the Intel Software College - Course Catalog at https://shale.intel.com/SoftwareCollege/CourseCatalog.asp.For additional technical product information including white papers about Intel compilers, open the page associated with your product at http://developer.intel.com/software/products/. xxix

http://developer.intel.com/software/products/https://shale.intel.com/SoftwareCollege/CourseCatalog.asp" target="_blank"http://developer.intel.com/software/products/

Intel Fortran Language ReferenceConventionsThe following table describes the typographic and terminology conventions used in this manual:

Typographic Conventions

Extensions to Fortran 95 This color indicates extensions to the Fortran 95 Standard. These extensions may or may not be implemented by other compilers that conform to the language standard.

AUTOMATIC, INTRINSIC, WRITE Uppercase letters indicate Fortran95/90 statements, data types, directives, and other syntax keywords. Examples of statement keywords are WRITE, INTEGER, DO, and OPEN.

option, option This italic type indicates an keyword arguments in syntax, new terms, emphasized text, or a book title. Most new terms are defined in the Glossary of the Language Reference.

CALL CPU_TIME This courier type indicates a code example, a derived type name, or a pathname.

CTRL Small capital letters indicate the names of keys and key sequences, such as CTRL+C.A plus indicates a combination of keys. For example, CTRL+E means to hold down the CTRL key while pressing the E key.

{choice1 | choice2} Braces and vertical bars indicate a choice of items. You can usually only choose one of the items in the braces.

[optional item] In syntax, single square brackets indicate items that are optional. In code examples, they are used to show arrays.

s[, s] A horizontal ellipsis (three dots in a row) following an item indicates that the item preceding the ellipsis can be repeated. In code examples, a horizontal ellipsis means that not all of the statements are shown.

Adobe Acrobat* An asterisk at the end of a word or name indicates it is a third-party product trademark.

Terminology Conventions

compiler option This term refers to Linux* options and Windows* options that can be used on the compiler command line.

cat(1) This format refers to an online reference page; the section number of the page is shown in parentheses. For example, a reference to cat(1) indicates that you can find the material on the cat command in Section 1 of the reference pages. To read online reference pages, use the man command. Your operating system documentation also includes reference page descriptions. xxx

About This ManualThe following example shows how this manual's typographic conventions are used to indicate the syntax of the PARAMETER statement:

PARAMETER [(] c = expr [, c = expr]...[)] This syntax shows that when you use this statement, you must specify the following: The keyword PARAMETER. An optional left parenthesis.

Intel Fortran This term refers to the name of the common compiler language supported by the Intel Visual Fortran Compiler for Windows* and Intel Fortran Compiler for Linux* products. For more information on these compilers, see http://developer.intel.com/software/products/.

Fortran This term refers to language information that is common to ANSI FORTRAN 77, ANSI/ISO Fortran 95/90, and Intel Fortran.

Fortran 95/90 This term refers to language information that is common to ANSI/ISO Fortran 95 and ANSI/ISO Fortran 90.

Fortran 95 This term refers to language features of ANSI/ISO Fortran 95.

Fortran 90 This term refers to language features of ANSI/ISO Fortran 90.

Windows systems This term refers to all supported Microsoft* Windows operating systems. (See also Platform Labels.)

Linux systems This term refers to all supported Linux operating systems. (See also Platform Labels.)

integer This term refers to the INTEGER(KIND=1), INTEGER(KIND=2), INTEGER (INTEGER(KIND=4)), and INTEGER(KIND=8) data types as a group.

real This term refers to the REAL (REAL(KIND=4)), DOUBLE PRECISION (REAL(KIND=8)), and REAL(KIND=16) data types as a group.

REAL This term refers to the default data type of objects declared to be REAL. REAL is equivalent to REAL(KIND=4), unless a compiler option specifies otherwise.

complex This term refers to the COMPLEX (COMPLEX(KIND=4)), DOUBLE COMPLEX (COMPLEX(KIND=8)), and COMPLEX(KIND=16) data types as a group.

logical This term refers to the LOGICAL(KIND=1), LOGICAL(KIND=2), LOGICAL (LOGICAL(KIND=4)), and LOGICAL(KIND=8) data types as a group.

This symbol indicates a nonprinting tab character.

This symbol indicates a nonprinting blank character.xxxi

http://developer.intel.com/software/products/

Intel Fortran Language Reference One or more c = expr items, where c is a named constant and expr is a value. If you want to specify more than one c = expr item, a comma must separate the items.The three dots following the syntax mean you can enter as many of these sequences (a comma, followed by c = expr) as you like.

An optional terminating right parenthesis. If you used the optional left parenthesis, you must use the terminating right parenthesis.

The colored brackets ([ ]) indicate that the parentheses are optional only as an extension to standard Fortran 95.

Platform Labels

A platform is a combination of operating system and central processing unit (CPU) that provides a distinct environment in which to use a product (in this case, a language). This manual contains information for the following language platforms:

Information in this manual applies to all supported platforms unless it is otherwise labeled for a specific platform (or platforms), as follows:

For example, the IOFOCUS specifier (for an OPEN statement) is labeled "(W*32, W*64)", so this specifier is valid only on Windows operating systems.

Platform1

1. For the latest information on the current language platforms, see the online Release Notes.

Language Operating System CPU

Intel Fortran Linux IA-32

Linux Intel Itanium

Microsoft* Windows* 2000 IA-32

Microsoft Windows NT* 4.0 IA-32

Microsoft Windows XP* IA-32

Microsoft Windows XP Intel Itanium

L*X Applies to Linux* on Intel IA-32 processors and Intel Itanium processors.

L*X32 Applies to Linux on Intel IA-32 processors.

L*X64 Applies to Linux on Intel Itanium processors.

W*32 Applies to Microsoft Windows* 2000, Windows XP, and Windows NT* 4.0 on Intel IA-32 processors.

W*64 Applies to Microsoft Windows XP operating systems on Intel Itanium processors.

i32 Applies to 32-bit operating systems on Intel IA-32 processors.

i64 Applies to 64-bit operating systems on Intel Itanium processors.xxxii

About This Manualxxxiii

Intel Fortran Language Referencexxxiv

Overview 1

This chapter discusses Intel Fortran standards conformance and language compatibility, and provides an overview of Fortran 95, Fortran 90, and proposed Fortran 2003 features.

Fortran 95 includes Fortran 90 and most features of FORTRAN 77. Fortran 90 is a superset that includes FORTRAN 77. Intel Fortran fully supports the Fortran 95, Fortran 90, and FORTRAN 77 Standards.

Figure 1-1 Graphic Representation of Intel Fortran

Fortran 95

FortranExtensions

Fortran 90

FORTRAN 771-1

1 Intel Fortran Language Reference

Language Standards Conformance

Intel Fortran conforms to American National Standard Fortran 95 (ANSI X3J3/96-007)1, American National Standard Fortran 90 (ANSI X3.198-1992)2, and includes support for some features in proposed standard Fortran 2003. The ANSI committee X3J3 is currently answering questions of interpretation of Fortran 95 and Fortran 90 language features. Any answers given by the ANSI committee that are related to features implemented in Intel Fortran may result in changes in future releases of the Intel Fortran compiler, even if the changes produce incompatibilities with earlier releases of Intel Fortran.Intel Fortran provides a number of extensions to the Fortran 95 Standard. In the language reference manual, extensions are displayed in this color. Intel Fortran also includes support for programs that conform to the previous Fortran standards (ANSI X3.9-1978 and ANSI X3.0-1966), the International Standards Organization standard ISO 1539-1980 (E), the Federal Information Pr