Lab 1 Recap: some new commands

randi(maxVal, numRows, numCols)

Produces an array with the specified number of rows and columns. Each entry in the array is a random integer between 1 and maxVal.

Example:

>>myMatrix = randi(6, 2, 3)

myMatrix =

4 6 1

2 3 4

Lab 1 Recap: some new commands

someArray == someValueProduces an array with the same size as someArray. The new array has a 1 in positions where someArray has the value someValue, and 0 otherwise.

Example:

>>myMatrix == 4

ans =

1 0 0

0 0 1

from previous slide

Lab 1 Recap: some new commands

find(someVector)

Returns the positions of the nonzero entries in someVector.

Example:

>>find([0 0 3 0 2 0 0 1])

ans =

3 5 8

Lab 1 Recap: simulate die tosses

>>dieTosses = randi(4, 1, 12)

>>dieTosses = randi(4, 1, 12)

‣ 1 x 12 array dieTosses is created

Lab 1 Recap: simulate die tosses

>>dieTosses = randi(4, 1, 12)

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

‣ 1 x 12 array dieTosses is created

Lab 1 Recap: simulate die tosses

>>dieTosses = randi(4, 1, 12)

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

‣ array is filled with random integers between 1 and 4

Lab 1 Recap: simulate die tosses

>>dieTosses = randi(4, 1, 12)

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

‣ array is filled with random integers between 1 and 4

Lab 1 Recap: simulate die tosses

>>dieTosses = randi(4, 1, 12)

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

‣ array is filled with random integers between 1 and 4

‣ these are our simulated die tosses

Lab 1 Recap: simulate die tosses

>>

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

Lab 1 Recap: simulate die tosses

>>

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

Lab 1 Recap: simulate die tosses

Lab 1 Recap: flag the 4’s using ==

>>myFours = (dieTosses == 4)

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

>>myFours = (dieTosses == 4)

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

‣ 1 x 12 array myFours is created

Lab 1 Recap: flag the 4’s using ==

>>myFours = (dieTosses == 4)

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

myFours (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

‣ 1 x 12 array myFours is created

Lab 1 Recap: flag the 4’s using ==

>>myFours = (dieTosses == 4)

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

myFours (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

‣ myFours has a 1 in every position that dieTosses has a 4, and 0’s elsewhere

Lab 1 Recap: flag the 4’s using ==

>>myFours = (dieTosses == 4)

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 1 0 1 0 0 0 0 1 1 0 1

myFours (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

‣ myFours has a 1 in every position that dieTosses has a 4, and 0’s elsewhere

Lab 1 Recap: flag the 4’s using ==

>>myFours = (dieTosses == 4)

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 1 0 1 0 0 0 0 1 1 0 1

myFours (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

‣ Question: what will this command do?

Lab 1 Recap: flag the 4’s using ==

>>myFours = (dieTosses == 4)

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 1 0 1 0 0 0 0 1 1 0 1

myFours (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

‣ Question: what will this command do?

>>numFours = sum(myFours)

Lab 1 Recap: flag the 4’s using ==

>>

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 1 0 1 0 0 0 0 1 1 0 1

myFours (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

Lab 1 Recap: flag the 4’s using ==

>>fourTimes = find(myFours)

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 1 0 1 0 0 0 0 1 1 0 1

myFours (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

Lab 1 Recap: find times of the fours

>>fourTimes = find(myFours)

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 1 0 1 0 0 0 0 1 1 0 1

myFours (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

‣ find(myFours) returns the positions of the nonzero entries in myFours

Lab 1 Recap: find times of the fours

>>fourTimes = find(myFours)

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 1 0 1 0 0 0 0 1 1 0 1

myFours (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

‣ find(myFours) returns the positions of the nonzero entries in myFours

Lab 1 Recap: find times of the fours

>>fourTimes = find(myFours)

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 1 0 1 0 0 0 0 1 1 0 1

myFours (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

‣ find(myFours) returns the positions of the nonzero entries in myFours

Lab 1 Recap: find times of the fours

>>fourTimes = find(myFours)

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 1 0 1 0 0 0 0 1 1 0 1

myFours (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

‣ find(myFours) returns the positions of the nonzero entries in myFours

Lab 1 Recap: find times of the fours

>>fourTimes = find(myFours)

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 1 0 1 0 0 0 0 1 1 0 1

myFours (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

‣ find(myFours) returns the positions of the nonzero entries in myFours

Lab 1 Recap: find times of the fours

>>fourTimes = find(myFours)

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 1 0 1 0 0 0 0 1 1 0 1

myFours (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

‣ find(myFours) returns the positions of the nonzero entries in myFours

Lab 1 Recap: find times of the fours

>>fourTimes = find(myFours)

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 1 0 1 0 0 0 0 1 1 0 1

myFours (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

‣ find(myFours) returns the positions of the nonzero entries in myFours

Lab 1 Recap: find times of the fours

>>fourTimes = find(myFours)

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 1 0 1 0 0 0 0 1 1 0 1

myFours (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 2 4 9 10 12

fourTimes (1 x 6 array)

1 2 3 4 5 6

Lab 1 Recap: find times of the fours

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 1 0 1 0 0 0 0 1 1 0 1

myFours (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 2 4 9 10 12

fourTimes (1 x 6 array)

1 2 3 4 5 6

Lab 1 Recap: find times of the fours

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 1 0 1 0 0 0 0 1 1 0 1

myFours (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 2 4 9 10 12

fourTimes (1 x 6 array)

1 2 3 4 5 6

Lab 1 Recap: find times of the fours

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 1 0 1 0 0 0 0 1 1 0 1

myFours (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 2 4 9 10 12

fourTimes (1 x 6 array)

1 2 3 4 5 6

‣ Question: what will this command do?

Lab 1 Recap: find times of the fours

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 1 0 1 0 0 0 0 1 1 0 1

myFours (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 2 4 9 10 12

fourTimes (1 x 6 array)

1 2 3 4 5 6

‣ Question: what will this command do?>>whatIsThis = fourTimes(5)

Lab 1 Recap: find times of the fours

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 1 0 1 0 0 0 0 1 1 0 1

myFours (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 2 4 9 10 12

fourTimes (1 x 6 array)

1 2 3 4 5 6

‣ Question: what will this command do?>>whatIsThis = fourTimes(5)

Lab 1 Recap: find times of the fours

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 1 0 1 0 0 0 0 1 1 0 1

myFours (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 2 4 9 10 12

fourTimes (1 x 6 array)

1 2 3 4 5 6

‣ Question: what will this command do?>>whatIsThis = fourTimes(5)

Lab 1 Recap: find times of the fours

4 4 1 4 3 1 2 3 4 4 1 4

dieTosses (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 1 0 1 0 0 0 0 1 1 0 1

myFours (1 x 12 array)

1 2 3 4 5 6 7 8 9 10 11 12

1 2 4 9 10 12

fourTimes (1 x 6 array)

1 2 3 4 5 6

‣ Question: what will this command do?>>whatIsThis = fourTimes(5)

Lab 1 Recap: find times of the fours