Comparison operators in MATLAB - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this MATLAB code using comparison operators?

Consider the following MATLAB code snippet. What will be the output displayed in the command window?

MATLAB

a = 5;
b = 10;
result = (a >= 5) & (b < 10);
disp(result);

A 1

B Logical array with elements [1 0]

C 0

D Error: Undefined function or variable 'result'.

💡 Hint

Remember that & is the element-wise AND operator and both conditions must be true.

The first condition (a >= 5) is true (1), but the second condition (b < 10) is false (0). Using & operator, true & false results in false (0). So, the output is 0.

❓ Predict Output

intermediate

What does this MATLAB code output when comparing arrays?

What will be the output of this MATLAB code?

MATLAB

x = [1 2 3 4];
y = [1 3 2 4];
result = x == y;
disp(result);

A [1 0 0 1]

B [0 1 1 0]

C 1

D Error: Matrix dimensions must agree.

💡 Hint

The == operator compares elements at the same positions.

The comparison x == y checks each element: 1==1 (true=1), 2==3 (false=0), 3==2 (false=0), 4==4 (true=1). So the output is [1 0 0 1].

❓ Predict Output

advanced

What is the output of this MATLAB code using relational operators with matrices?

Given the following code, what will be the output?

MATLAB

A = [1 4; 3 2];
B = [2 3; 3 5];
result = A < B;
disp(result);

A [1 1; 0 1]

B [0 0; 0 0]

C [1 1; 1 1]

D [1 0; 0 1]

💡 Hint

The < operator compares each element of A with the corresponding element of B.

Comparisons: 1<2 (1), 4<3 (0), 3<3 (0), 2<5 (1). So the result matrix is [1 0; 0 1], which is option D.

❓ Predict Output

advanced

What is the output of this MATLAB code using the '==' operator with strings?

What will this code display?

MATLAB

str1 = 'hello';
str2 = 'Hello';
result = str1 == str2;
disp(result);

A [1 0 0 0 0]

B [0 1 1 1 1]

C [0 0 0 0 0]

D Error: Matrix dimensions must agree.

💡 Hint

The == operator compares characters by their ASCII codes.

Comparing 'h' (ASCII 104) with 'H' (ASCII 72) is false (0), so option B is incorrect. Actually, the first characters differ, so first element is 0. The rest: 'e'=='e' (1), 'l'=='l' (1), 'l'=='l' (1), 'o'=='o' (1). So output is [0 1 1 1 1].

❓ Predict Output

expert

What is the output of this MATLAB code using logical operators with mixed data types?

Analyze the following code and determine the output.

MATLAB

a = [true false true];
b = [1 0 2];
result = a & (b > 1);
disp(result);

A [0 0 1]

B [1 0 1]

C Error: Matrix dimensions must agree.

D [1 1 1]

💡 Hint

Logical AND & works element-wise and b > 1 returns a logical array.

b > 1 is [false false true] or [0 0 1]. a is [true false true] or [1 0 1]. Element-wise AND: 1&0=0, 0&0=0, 1&1=1. So result is [0 0 1].

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