Colon operator for ranges in MATLAB - Step-by-Step Execution

Concept Flow - Colon operator for ranges

Start with start_value

↓

Check if next_value <= end_value

Yes↓

Add next_value to range

↓

Increment next_value by step

Back to Check↓

End range

↩Back to Check

The colon operator creates a range starting from a start value, increasing by a step, until it reaches or passes the end value.

Execution Sample

MATLAB

range = 1:2:7;
disp(range);

Creates a range starting at 1, stepping by 2, up to 7, then displays it.

Execution Table

Step	Current Value	Condition (<=7)	Action	Range So Far
1	1	1 <= 7 (True)	Add 1	[1]
2	3	3 <= 7 (True)	Add 3	[1, 3]
3	5	5 <= 7 (True)	Add 5	[1, 3, 5]
4	7	7 <= 7 (True)	Add 7	[1, 3, 5, 7]
5	9	9 <= 7 (False)	Stop	[1, 3, 5, 7]

💡 Next value 9 is greater than end value 7, so range creation stops.

Variable Tracker

Variable	Start	After 1	After 2	After 3	After 4	Final
next_value	1	3	5	7	9	9
range	[]	[1]	[1, 3]	[1, 3, 5]	[1, 3, 5, 7]	[1, 3, 5, 7]

Key Moments - 3 Insights

Why does the range include 7 even though the step is 2?

Because the condition checks if the current value is less than or equal to the end value (7). Since 7 <= 7 is true, 7 is included (see execution_table step 4).

What happens if the next value after increment is greater than the end value?

The range stops growing and the loop ends (see execution_table step 5 where 9 > 7 stops the process).

Can the colon operator create ranges with negative steps?

Yes, but the condition changes to check if the current value is greater than or equal to the end value to stop correctly.

Visual Quiz - 3 Questions

Look at the execution_table, what is the range after step 3?

A [1, 3, 5, 7]

B [1, 3, 5]

C [1, 3]

D [1]

💡 Hint

Check the 'Range So Far' column at step 3 in the execution_table.

At which step does the condition become false and stop the range creation?

A Step 3

B Step 4

C Step 5

D Step 2

💡 Hint

Look at the 'Condition' column where it shows false in the execution_table.

If the step was changed to 3, what would be the last value included in the range?

A 7

B 3

C 4

D 6

💡 Hint

Think about adding 3 each time starting from 1 until exceeding 7.

Concept Snapshot

Colon operator syntax: start:step:end
Creates a vector from start to end, adding step each time.
Includes end if it matches exactly.
Stops when next value passes end.
Step can be positive or negative.

Full Transcript

The colon operator in MATLAB creates a range of numbers starting from a start value, increasing by a step, until it reaches or passes the end value. For example, 1:2:7 creates the numbers 1, 3, 5, and 7. Each step adds 2 to the previous number. The process stops when the next number would be greater than 7. This is shown step-by-step in the execution table. The variable tracker shows how the current value and the range change after each step. Key points include that the end value is included if the current value equals it, and the range stops when the next value exceeds the end. The colon operator can also work with negative steps to create decreasing ranges.