basics of matlab (11cs)

Basics of MatlabBy Ali Asghar Manjotho

Lecturer department of computer systems engineering, MUET, Jamshoro.

Matrix• Collection of rows and columns.• Represented by capital alphabets e.g. A, B, X.• Matrix elements are represented by small

alphabets e.g. x, y, z.• A =

• >> A = [1,2,3;4,5,6;7,8,9] or• >> A = [1 2 3; 4 5 6; 7 8 9]

Vector• Vector is a matrix having either single row or

single column.• Single row matrix is called row vector.• Single column matrix is called column vector.•

• >> B = [4 2 8]• >> C = [7; 3; 9]

Vector & linspace

• >> D = [5 10 15 20 25 30 35 40 45 50]• >> D = 5:5:50• >> D = linspace(5,50,10)

• >> E = [1:1:5 100:2:108]• >> E = [linspace(1,5,5) linspace(100,108,5)]

• linspace(X1,X2,N) generates linearly spaced vector, where X1 = start, X2 = end and N = number of points.

Vector & Transpose•

• >> F = [5 10 15]• >> F’

• >> G = [2:2:10]’• >> G = [linspace(2,10,5)]’

Matrix and Vector Indices

• >> H = [11 12 13 14 15; 16 17 18 19 20; 21 22

23 24 25; 26 27 28 29 30; 31 32 33 34 35]


• Element at 2nd row, 5th column

• >> H(2,5) ans = 20


• Element at 5th row, 2nd column

• >> H(5,2) (element at 5th row, 2nd column)

ans = 32


• Elements at row 3

• >> H(3,1:5) ans = 21 22 23 24 25

• >> H(3,:) ans = 21 22 23 24 25


• Elements at row 5

• >> H(5,1:5) ans = 31 32 33 34 35

• >> H(5,:) ans = 31 32 33 34 35


• Elements at column 4

• >> H(1:5,4)• >> H(:,4) ans =

1419242934


• Elements at row 3&4 column 2&3

• >> H(3:4,2:3)

ans = 22 2327 28


• Elements at row 2 to 4 column 3 to 5

• >> H(2:4,3:5)

ans = 18 19 2023 24 2628 29 30


• >> H(logical([0 1 0 1 0; 0 0 0 0 0; 0 0 0 1 0; 1 0 0 0 0; 0 0 1 0 1]))


• >> I = [4 2 5 6 7 3 6]


• >> I(5) ans = 7


• >> I(2:5) ans = 2 5 6 7

Replacing matrix elements

• >> H(2,4) = 60

Replacing matrix elements

• >> H(1:2,2:3) = [20 30; 40 50]

Deleting matrix elements

• >> I(5) = []


• >> I(4:6) = []


• >> H(1,:) = []


• >> H(:,4:5) = []

Zeros function• >> zeros(5,5)

Ones function• >> ones(5,5)

Ones function• >> 7*ones(5,5)

Rand function• >> rand(5,5)

Rand function• >> 100*rand(5,5)

Rand function• >> fix(100*rand(5,5))

Rand function• >> 1 + fix(100*rand(5,5))

Randint function• >> randint(5,5,[50 100])

Magic function• >> magic(3)

Diagonal of matrix

• >> diag(H)

Inverse of matrix

• >> inv(H)

Determinant of matrix

• >> det(H)

Number of elements

• >> numel(H)

Size of matrix

• >> size(H)

Max function

• >> max(H)

• >> max(max(H))

Min function

• >> min(H)

• >> min(min(H))

Sum function

• >> sum(H)

• >> sum(sum(H))

Mean function

• >> mean(H)

• >> mean(mean(H))

Matrix & Array operations

•

• >> J = [5 8; 4 1]• >> K = [1 2; 2 1]• >> J + K


•

• >> J - K


•

• >> J * K


•

• >> J .* K

Plotting Functions

basics of matlab (11cs)

Engineering