Multiple outputs in MATLAB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does 'multiple outputs' mean in MATLAB functions?

It means a function can return more than one result at the same time, separated by commas.

beginner

How do you define a MATLAB function that returns two outputs?

Use square brackets around output names in the function definition, like:
function [out1, out2] = myFunc(input)

beginner

How do you call a MATLAB function that returns multiple outputs?

Assign outputs to variables using square brackets, like:
[a, b] = myFunc(x)

intermediate

What happens if you call a MATLAB function with multiple outputs but only ask for one?

MATLAB returns only the first output and ignores the others.

beginner

Show a simple MATLAB function that returns the sum and product of two numbers.

function [sumVal, prodVal] = sumAndProduct(a, b) sumVal = a + b; prodVal = a * b; end

How do you define multiple outputs in a MATLAB function?

A Use square brackets around output variables in the function header

B Separate outputs with semicolons

C Use curly braces around outputs

D List outputs separated by spaces

In MATLAB, multiple outputs are defined by enclosing output variable names in square brackets in the function definition.

What will MATLAB return if you call a function with multiple outputs but only assign one variable?

A An error

B All outputs as a list

C The last output

D Only the first output

MATLAB returns only the first output if you assign only one variable when calling a function with multiple outputs.

How do you capture two outputs from a MATLAB function named 'calc'?

A x, y = calc()

B [x, y] = calc()

C x = calc()

D {x, y} = calc()

Use square brackets to capture multiple outputs: [x, y] = calc()

Which of these is a valid MATLAB function header for multiple outputs?

A function [out1, out2] = myFunc(input)

B function out1, out2 = myFunc(input)

C function {out1, out2} = myFunc(input)

D function (out1, out2) = myFunc(input)

Only option D uses correct MATLAB syntax with square brackets for multiple outputs.

If a function returns three outputs but you only want the second, how can you get it?

A second = func(2)

B [second] = func()

C [~, second, ~] = func()

D func(second)

Use the tilde (~) to ignore unwanted outputs and capture the second output.

Explain how to create and use a MATLAB function that returns multiple outputs.

Think about how you write the function header and how you get the results when calling it.

Describe what happens if you call a MATLAB function with multiple outputs but only assign one variable to receive the result.

Consider MATLAB's default behavior when fewer outputs are requested.

Practice

1. In MATLAB, how do you define a function that returns multiple outputs?

easy

A. Separate output variables with commas without brackets.

B. Use square brackets around output variables in the function definition.

C. Use parentheses around output variables in the function definition.

D. Define each output in a separate function.

Solution

1. Step 1: Understand MATLAB function output syntax

   MATLAB requires multiple outputs to be enclosed in square brackets in the function definition. Only Use square brackets around output variables in the function definition. correctly uses square brackets; others are invalid syntax or incorrect approach.

2. Final Answer:

   Use square brackets around output variables in the function definition. -> Option B

3. Quick Check:

   Multiple outputs = square brackets [OK]

Hint: Remember: multiple outputs always use square brackets [OK]

Common Mistakes:

• Using parentheses instead of square brackets
• Listing outputs without any brackets
• Trying to define outputs in separate functions

2. Which of the following is the correct syntax to call a MATLAB function myFunc that returns two outputs?

easy

A. [a, b] = myFunc(x);

B. a, b = myFunc(x);

C. (a, b) = myFunc(x);

D. a = myFunc(x); b = myFunc(x);

Solution

1. Step 1: Recall MATLAB function call syntax for multiple outputs

   Multiple outputs must be captured using square brackets on the left side of the assignment. [a, b] = myFunc(x); uses correct square brackets; B and C use invalid syntax; A calls function twice, not multiple outputs.

2. Final Answer:

   [a, b] = myFunc(x); -> Option A

3. Quick Check:

   Multiple outputs call = square brackets [OK]

Hint: Use square brackets to capture multiple outputs when calling [OK]

Common Mistakes:

• Using parentheses or commas without brackets
• Calling function multiple times instead of one call
• Missing brackets around output variables

3. What is the output of this MATLAB code?

function [sumVal, diffVal] = calc(a, b)
    sumVal = a + b;
    diffVal = a - b;
end

[x, y] = calc(5, 3);

What are the values of x and y?

medium

A. x = 5, y = 3

B. x = 2, y = 8

C. x = 8, y = 2

D. x = 15, y = 2

Solution

1. Step 1: Trace function execution and match outputs

   The function returns sumVal = a + b = 5 + 3 = 8 and diffVal = a - b = 5 - 3 = 2. x receives sumVal (8), y receives diffVal (2).

2. Final Answer:

   x = 8, y = 2 -> Option C

3. Quick Check:

   sum = 8, diff = 2 [OK]

Hint: First output = sum, second output = difference [OK]

Common Mistakes:

• Swapping order of outputs
• Confusing inputs with outputs
• Adding instead of subtracting for difference

4. Identify the error in this MATLAB function that tries to return two outputs:

function [a, b] = wrongFunc(x)
    a = x * 2;
    b = x + 3
end

medium

A. Square brackets not allowed in output

B. Function must return only one output

C. Function name does not match file name

D. Missing semicolon after assigning b

Solution

1. Step 1: Check syntax line by line

   Line assigning b lacks a semicolon, causing output to print unexpectedly. Multiple outputs with square brackets are allowed; function name matching file is good practice but not error here.

2. Final Answer:

   Missing semicolon after assigning b -> Option D

3. Quick Check:

   Missing semicolon = syntax error [OK]

Hint: Always end statements with semicolon to avoid output [OK]

Common Mistakes:

• Ignoring missing semicolons
• Thinking multiple outputs are not allowed
• Confusing function name and file name mismatch as error

5. You want to write a MATLAB function stats that takes a vector and returns three outputs: the mean, median, and standard deviation. Which function header and call are correct?

hard

A. Function: function [m, med, s] = stats(v)Call: [meanVal, medianVal, stdVal] = stats(data);

B. Function: function (m, med, s) = stats(v)Call: (meanVal, medianVal, stdVal) = stats(data);

C. Function: function m, med, s = stats(v)Call: meanVal, medianVal, stdVal = stats(data);

D. Function: function stats(v) returns m, med, sCall: stats(data)

Solution

1. Step 1: Verify function header and call syntax

   Multiple outputs must use square brackets in the function header: function [m, med, s] = stats(v) and in the call: [meanVal, medianVal, stdVal] = stats(data);. Others use invalid parentheses, commas without brackets, or incorrect formats.

2. Final Answer:

   Function and call with square brackets for multiple outputs -> Option A

3. Quick Check:

   Multiple outputs = square brackets in header and call [OK]

Hint: Use square brackets for multiple outputs in both function and call [OK]

Common Mistakes:

• Using parentheses instead of square brackets
• Not capturing all outputs in call
• Incorrect function header syntax