Colon operator for ranges in MATLAB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the colon operator (:) do in MATLAB when used like this: 1:5?

It creates a row vector with values starting at 1, increasing by 1, up to 5. So, the result is [1 2 3 4 5].

beginner

How do you use the colon operator to create a vector from 2 to 10 with a step size of 2?

You write 2:2:10. This means start at 2, add 2 each time, until you reach or pass 10. The result is [2 4 6 8 10].

intermediate

What happens if the step size in the colon operator is negative, like 5:-1:1?

It creates a vector starting at 5, decreasing by 1 each time, down to 1. So, the vector is [5 4 3 2 1].

intermediate

Can the colon operator create an empty vector? If yes, give an example.

Yes. For example, 1:-1:5 creates an empty vector because starting at 1 and decreasing by 1 will never reach 5. So, the result is [].

beginner

Explain the difference between 1:5 and 1:1:5 in MATLAB.

Both create the same vector [1 2 3 4 5]. The first uses the default step size of 1, while the second explicitly sets the step size to 1.

What is the result of 3:3:12 in MATLAB?

A [3 6 9]

B [3 6 9 12]

C [3 4 5 6 7 8 9 10 11 12]

D [3 6 9 12 15]

Starting at 3, adding 3 each time until 12 gives [3 6 9 12].

What does the expression 10:-2:2 produce?

A [10 8 6 4 2]

B [10 9 8 7 6 5 4 3 2]

C [2 4 6 8 10]

D []

Starting at 10, subtracting 2 each time down to 2 results in [10 8 6 4 2].

What happens if you run 1:0:5 in MATLAB?

A []

B [1 1 1 1 1]

C [1 2 3 4 5]

D Error due to zero step size

A step size of zero is invalid and causes an error.

Which of these creates an empty vector?

A 1:1:5

B 5:1:10

C 1:-1:5

D 10:-2:2

Starting at 1 and decreasing by 1 will never reach 5, so the vector is empty.

What is the default step size when using the colon operator like 4:9?

A 1

B 0

C -1

D Depends on the numbers

If no step size is given, MATLAB uses 1 by default.

Describe how to use the colon operator to create a vector with a custom step size.

Think about how you tell MATLAB where to start, how much to jump each time, and where to stop.

Explain what happens when the step size in the colon operator does not allow reaching the end value.

Consider if the step moves away from the end value instead of towards it.