Comparison operators in MATLAB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the == operator do in MATLAB?

The == operator checks if two values are equal. It returns true if they are the same, and false if they are different.

beginner

What is the difference between = and == in MATLAB?

= is used to assign a value to a variable, while == is used to compare two values for equality.

beginner

What does the ~= operator mean in MATLAB?

The ~= operator means "not equal to". It returns true if the two values are different, and false if they are the same.

beginner

How do you check if one number is greater than another in MATLAB?

Use the > operator. For example, 5 > 3 returns true because 5 is greater than 3.

beginner

What does the <= operator do in MATLAB?

The <= operator checks if the value on the left is less than or equal to the value on the right. It returns true if it is, otherwise false.

What will 3 == 3 return in MATLAB?

A false

B true

C 3

D Error

The == operator checks if two values are equal. Since 3 equals 3, it returns true.

Which operator checks if two values are NOT equal in MATLAB?

A !=

B ==

C ~=

D =

In MATLAB, ~= means "not equal to". The != operator is not used in MATLAB.

What does 5 <= 2 return?

A false

B true

C 5

D Error

5 is not less than or equal to 2, so 5 <= 2 returns false.

Which operator is used to assign a value to a variable in MATLAB?

A =

B ~=

C >

D ==

The = operator assigns a value to a variable, for example x = 5.

What will 7 > 10 return?

A true

B Error

C 7

D false

Since 7 is not greater than 10, the expression returns false.

Explain how to use comparison operators in MATLAB to compare two numbers.

Think about how you check if numbers are equal or different.

Describe the difference between assignment and comparison operators in MATLAB.

One sets a value, the other checks if values are the same.

Practice

1. What does the MATLAB expression 5 > 3 return?

easy

A. 0 (false)

B. 1 (true)

C. Error

D. 5

Solution

1. Step 1: Understand the comparison operator

   The operator > checks if the left value is greater than the right value.

2. Step 2: Compare the values 5 and 3

   Since 5 is greater than 3, the expression returns true, which is represented as 1 in MATLAB.

3. Final Answer:

   1 (true) -> Option B

4. Quick Check:

   5 > 3 = 1 [OK]

Hint: Greater than means left number bigger than right [OK]

Common Mistakes:

• Confusing true (1) with false (0)
• Thinking it returns the bigger number
• Using wrong operator like < instead of >

2. Which of the following is the correct MATLAB syntax to check if variable a is equal to 10?

easy

A. a = 10

B. a === 10

C. a != 10

D. a == 10

Solution

1. Step 1: Identify the equality operator in MATLAB

   MATLAB uses double equal signs == to test equality, not a single equal sign.

2. Step 2: Check each option

   a = 10 assigns 10 to a, not compare. a == 10 correctly compares a to 10. a === 10 uses triple equals which is invalid in MATLAB. a != 10 uses not equal operator incorrectly.

3. Final Answer:

   a == 10 -> Option D

4. Quick Check:

   Equality test uses == [OK]

Hint: Use double equals (==) to compare, single equals (=) assigns [OK]

Common Mistakes:

• Using single = instead of ==
• Using === which is not MATLAB syntax
• Confusing != with ~= for not equal

3. What is the output of the following MATLAB code?

a = [1 3 5]; b = [2 3 4]; result = a <= b;

medium

A. [1 1 0]

B. [1 0 0]

C. [0 1 1]

D. [0 0 1]

Solution

1. Step 1: Understand element-wise comparison

   The operator <= compares each element of a with the corresponding element of b.

2. Step 2: Compare each pair

   1 <= 2 is true (1), 3 <= 3 is true (1), 5 <= 4 is false (0).

3. Final Answer:

   [1 1 0] -> Option A

4. Quick Check:

   Element-wise <= comparison = [1 1 0] [OK]

Hint: Compare arrays element-wise for <= operator [OK]

Common Mistakes:

• Thinking it returns a single value
• Mixing up < and <= operators
• Forgetting element-wise comparison

4. Identify the error in this MATLAB code snippet:

if a = 5
    disp('Equal');
end

medium

A. Missing semicolon after assignment

B. disp function is incorrect

C. Using = instead of == in if condition

D. if statement needs parentheses

Solution

1. Step 1: Check the if condition syntax

   In MATLAB, the if condition requires a logical expression, not an assignment.

2. Step 2: Identify the operator mistake

   The code uses = which assigns 5 to a, instead of == which compares a to 5.

3. Final Answer:

   Using = instead of == in if condition -> Option C

4. Quick Check:

   Comparison uses ==, not = in conditions [OK]

Hint: Use == for comparison inside if, not = [OK]

Common Mistakes:

• Using = instead of ==
• Adding unnecessary parentheses
• Misusing disp function

5. Given two arrays A = [4 7 2 9] and B = [5 7 3 8], write a MATLAB expression using comparison operators to create a logical array that is true where elements of A are greater than or equal to B and false otherwise. What is the resulting array?

hard

A. [0 1 0 1]

B. [1 1 1 1]

C. [0 0 0 0]

D. [1 0 1 0]

Solution

1. Step 1: Use element-wise comparison operator

   Use the operator >= to compare each element of A with B element-wise.

2. Step 2: Compare each element pair

   4 >= 5 is false (0), 7 >= 7 is true (1), 2 >= 3 is false (0), 9 >= 8 is true (1).

3. Final Answer:

   [0 1 0 1] -> Option A

4. Quick Check:

   A >= B = [0 1 0 1] [OK]

Hint: Use >= for element-wise greater or equal comparison [OK]

Common Mistakes:

• Using > instead of >=
• Confusing logical array with numeric values
• Mixing element-wise with matrix operations