Functions

Question 1

Returning variables in a function

Answer 1

Function x=’function name’

//commands to execute

End

Where x is the variable in the function

Question 2

Returning multiple variables in a function

Answer 2

Function [x y z …] = ‘function name’

//commands to execute

End

Question 3

How to pass a variable(s) to functions from the command line

Answer 3

Function x=’function name’(y,z,a,b,…)

//commands to execute

End

Where y,z,a,b are variables that are passed to the function

Question 4

Structure of a function in MATLAB

Answer 4

Function ‘function name’

//commands to perform

End

Question 5

Functions and sub functions accessibility in a single .m file

Answer 5

Only the function placed at the top of the .m file can be accessed at the command line

Question 6

Creating global variables

Answer 6

Global ‘variable name’

Question 7

Pause MATLAB for a period of n seconds

Answer 7

Pause(n)

Question 8

What does max(variable/array/matrix) return

Answer 8

Max(variable/array/matrix) can return the max number and the position of the max number

Question 9

Generating random integer numbers

Generating random numbers with mean of 0 and standard deviation of 1

Answer 9

Integer= randi(integer range,size)

Normal distribution= randn(size)

Question 10

How to Change a variable to fixed point

Answer 10

Fix(variable)

Question 11

Generating zeros of a certain size
Generating ones of a certain size
Generating integers of a certain size

Answer 11

Zeros = zeros(size)
Ones = ones(size)
Integers = integer*ones(size)

Question 12

What does the return command in a function do

Answer 12

Stops the function from further executing and returning to the command line

Question 13

Purpose of nargin function for creating polymorphic functions

Answer 13

Returns number of actual input arguments given to the function

Eg if function is given 3 input arguments, nargin returns a value of 3

Function ‘function name’(x,y)

If ‘function name’(3,2) is called then nargin returns a value of 2 when used

Question 14

Purpose of nargout function for creating polymorphic functions

Answer 14

returns the number of output arguments requested by the function caller

Eg. If function called as [x y] = ‘function name’
Then nargout returns a value of 2

Question 15

What is the correct operator to use for 5 AND 6
What is the correct operator to use for 2 OR -2
What are these operators called
What is the correct operator to use for 5 AND [1 2 3]
What is the correct operator to use for 2 OR [-2 0 7]
What are these operators called

Answer 15

1. &&
2. ||

Scalar logical operators

1. &
2. |

Array logical operators

Question 16

Checking if a value is a scalar value

Checking if a variable is empty

Answer 16

1. Isscalar(value)

2. Isempty(variable)

Question 17

Creating variables that will maintain its contents each time a function is called

What does this variable initialize to

Answer 17

Persistent ‘variable name’

Persistent variables does not get cleared when a function is completed
It also initializes to an empty matrix on the first load

Question 18

Clearing a persistent variable in a function

Answer 18

1. Clear ‘function name’
2. Exit and reopen matlab
3. Saving the function

Question 19

How to create sections in a script

Answer 19

Add the %% at the start of each desired mew section

Question 20

How to make a function display error messages

Answer 20

Use the error(‘message’)

Error message automatically creates a new line

Question 21

How to create a for loop

Answer 21

For x = y:z

//operations to execute

End

Question 22

How to create a while loop

Answer 22

While //condition to meet not met

//operations to execute

End

Question 23

Function to check name, size, byte and type of a variable or all variables

Answer 23

Whos ‘variable name’

Whos

Question 24

What to add to skip an output argument

Eg for the max function

Answer 24

Replace the output argument with a ~

Max function is polymorphic, can take 2 output arguments. But if say, only the 2nd argument is desired, the 1st output argument can be skipped by using the ~ function

Eg [~ x] = max([1 2 3 4 5])

This will only return the location of the max value

Question 25

Checking if 2 variables are equal

What does it do, what does it return

Answer 25

Isequal(x,y)

Compares entire of x vs y instead of individual data in x & y

Returns 1 if equal