Relational expressions in MATLAB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if variable a is greater than 10.

MATLAB

result = (a [1] 10);

Drag options to blanks, or click blank then click option'

A<

B>

C==

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using < instead of >.

Using == which checks equality, not greater than.

The symbol > checks if a is greater than 10.

2fill in blank

medium

Complete the code to check if variable x is less than or equal to 5.

MATLAB

flag = (x [1] 5);

Drag options to blanks, or click blank then click option'

A<=

B>=

C==

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using >= which means greater than or equal.

Using == which checks equality only.

The symbol <= checks if x is less than or equal to 5.

3fill in blank

hard

Fix the error in the code to correctly check if y is not equal to 0.

MATLAB

isNonZero = (y [1] 0);

Drag options to blanks, or click blank then click option'

A~=

B!=

C==

D=

Attempts:

3 left

💡 Hint

Common Mistakes

Using != which is invalid in MATLAB.

Using = which is assignment, not comparison.

In MATLAB, ~=` means 'not equal to'. The symbol != is not valid in MATLAB.

4fill in blank

hard

Fill both blanks to create a logical array that is true where elements of vector v are greater than 3 and less than 8.

MATLAB

result = (v [1] 3) & (v [2] 8);

Drag options to blanks, or click blank then click option'

A>

B<

C>=

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using >= or <= which include equality, not asked here.

Swapping the symbols causing wrong logic.

The expression checks if elements are greater than 3 and less than 8 using > and <.

5fill in blank

hard

Fill all three blanks to create a logical array that is true where elements of array a are less than or equal to 10, greater than 0, and not equal to 5.

MATLAB

result = (a [1] 10) & (a [2] 0) & (a [3] 5);

Drag options to blanks, or click blank then click option'

A<=

B>

C~=

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using == instead of ~=` for not equal.

Mixing up <= and <.

Using invalid operators like !=.

The code checks three conditions: less than or equal to 10 (<=), greater than 0 (>), and not equal to 5 (~=`).

Practice

1. Which of the following relational operators in MATLAB checks if two values are NOT equal?

easy

A. ==

B. <=

C. >=

D. ~=

Solution

1. Step 1: Understand the meaning of relational operators

   The operator == checks equality, ~= checks inequality, and >=, <= check greater or equal and less or equal respectively.

2. Step 2: Identify the operator for NOT equal

   The operator ~= means NOT equal in MATLAB.

3. Final Answer:

   ~= -> Option D

4. Quick Check:

   NOT equal operator = ~= [OK]

Hint: Remember: ~= means NOT equal in MATLAB [OK]

Common Mistakes:

• Confusing == with ~=
• Using = instead of ==
• Mixing up >= and >

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

easy

A. a >== 10

B. a >= 10

C. a =< 10

D. a => 10

Solution

1. Step 1: Recall MATLAB relational operator syntax

   MATLAB uses >= to mean greater than or equal to.

2. Step 2: Check each option for correct syntax

   a >= 10 uses >= correctly. Options A, B, and C use invalid or reversed operators.

3. Final Answer:

   a >= 10 -> Option B

4. Quick Check:

   Greater or equal operator = >= [OK]

Hint: Use >= for greater or equal, not => or =< [OK]

Common Mistakes:

• Writing => instead of >=
• Writing =< instead of <=
• Adding extra = signs

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

a = 5; b = 7;
result = (a < b) & (b <= 7);
disp(result);

medium

A. 1

B. 0

C. Error

D. [1 0]

Solution

1. Step 1: Evaluate each relational expression

   a < b is 5 < 7 which is true (1). b <= 7 is 7 <= 7 which is true (1).

2. Step 2: Apply logical AND operator &

   Both expressions are true, so (1 & 1) equals 1 (true).

3. Final Answer:

   1 -> Option A

4. Quick Check:

   True & True = 1 [OK]

Hint: True & True gives 1, false & anything gives 0 [OK]

Common Mistakes:

• Confusing & with &&
• Expecting output as logical word instead of 1
• Misreading <= operator

4. Identify the error in this MATLAB code snippet:

x = 10;
if x = 10
    disp('Equal to 10');
end

medium

A. Using = instead of == in if condition

B. Missing semicolon after disp statement

C. Incorrect use of end keyword

D. Variable x is not initialized

Solution

1. Step 1: Check the if condition syntax

   In MATLAB, = is assignment, == is comparison. Using = in if causes error.

2. Step 2: Confirm other parts are correct

   Semicolon after disp is optional, end is correctly used, x is initialized.

3. Final Answer:

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

4. Quick Check:

   Comparison needs ==, not = [OK]

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

Common Mistakes:

• Using = instead of ==
• Thinking semicolon is mandatory after disp
• Misplacing end keyword

5. Given a vector v = [3, 6, 9, 12], which MATLAB expression returns a logical array indicating elements greater than 5 and less than or equal to 10?

hard

A. v > (5 & v) <= 10

B. v > 5 && v <= 10

C. (v > 5) & (v <= 10)

D. (v > 5) | (v <= 10)

Solution

1. Step 1: Understand vector relational operations

   Relational operators applied to vectors return logical arrays element-wise.

2. Step 2: Combine conditions correctly with parentheses and &

   Use parentheses around each condition: (v > 5) & (v <= 10) to get elements satisfying both.

3. Step 3: Check other options for syntax errors

   v > 5 && v <= 10 uses short-circuit &&, invalid for vectors. v > (5 & v) <= 10 is invalid syntax. (v > 5) | (v <= 10) uses OR instead of AND.

4. Final Answer:

   (v > 5) & (v <= 10) -> Option C

5. Quick Check:

   Use parentheses with & for combined conditions [OK]

Hint: Always use parentheses around each relational condition [OK]

Common Mistakes:

• Using && instead of & for array operations
• Using | instead of & for AND
• Writing invalid combined expressions