MATLAB vs Python vs R comparison - Practice Questions

Challenge - 5 Problems

❓ Predict Output

intermediate

Output difference in matrix multiplication

What is the output of this MATLAB code snippet?

A = [1 2; 3 4]; B = [5 6; 7 8]; C = A * B;

MATLAB

A = [1 2; 3 4];
B = [5 6; 7 8];
C = A * B;

A [19 22; 43 50]

B [17 20; 39 46]

C [5 12; 21 32]

D [12 16; 28 40]

💡 Hint

Remember that * in MATLAB means matrix multiplication, not element-wise.

In MATLAB, * performs matrix multiplication. Multiplying A and B results in [[19 22]; [43 50]].

❓ Predict Output

intermediate

Python vs MATLAB element-wise multiplication output

What is the output of this Python code snippet using NumPy?

import numpy as np
A = np.array([[1, 2], [3, 4]])
B = np.array([[5, 6], [7, 8]])
C = A * B
print(C)

MATLAB

import numpy as np
A = np.array([[1, 2], [3, 4]])
B = np.array([[5, 6], [7, 8]])
C = A * B
print(C)

A

[[19 22]
 [43 50]]

B

[[1 2]
 [3 4]]

C

[[5 6]
 [7 8]]

D

[[5 12]
 [21 32]]

💡 Hint

In NumPy, * means element-wise multiplication, unlike MATLAB's *.

NumPy's * operator multiplies elements one by one, so C is [[5 12]; [21 32]].

❓ Predict Output

advanced

R vector recycling behavior output

What is the output of this R code?

v1 <- c(1, 2, 3, 4)
v2 <- c(10, 20)
v3 <- v1 + v2
print(v3)

MATLAB

v1 <- c(1, 2, 3, 4)
v2 <- c(10, 20)
v3 <- v1 + v2
print(v3)

A [10 20 10 20]

B [11 22 13 24]

C [11 22 33 44]

D Error: vectors must be same length

💡 Hint

R recycles shorter vectors to match the length of longer vectors.

R repeats v2 elements to add to v1: 1+10=11, 2+20=22, 3+10=13, 4+20=24.

🧠 Conceptual

advanced

Key difference in indexing between MATLAB and Python

Which statement correctly describes a key difference in indexing between MATLAB and Python?

A MATLAB uses 1-based indexing; Python uses 0-based indexing.

B Both MATLAB and Python use 0-based indexing.

C MATLAB uses 0-based indexing; Python uses 1-based indexing.

D Both MATLAB and Python use 1-based indexing.

💡 Hint

Think about the first element position in each language.

MATLAB arrays start at index 1, while Python arrays start at index 0.

❓ Predict Output

expert

Output of mixed language style code snippet

What is the output of this MATLAB code?

arr = [1, 2, 3, 4];
result = sum(arr > 2);
disp(result);

MATLAB

arr = [1, 2, 3, 4];
result = sum(arr > 2);
disp(result);

A Error: Unsupported operation

B 7

C 2

D 3

💡 Hint

arr > 2 creates a logical array; sum counts true values.

Elements greater than 2 are 3 and 4, so sum counts 2 true values.