MATLAB Matrix and Array Operations 4

Question 1

What does logical indexing `A(A > 5)` return for matrix A = [1 6; 3 8]?

Accepted Answer

A column vector [6; 8]

Answer

Logical indexing selects elements satisfying the condition and returns them as a column vector in column-major order.

Question 2

What is the MATLAB operator for element-wise division?

Accepted Answer

./

Answer

`./` divides corresponding elements of two arrays, whereas `/` performs matrix right division.

Question 3

What does `fliplr([1 2 3; 4 5 6])` return?

Accepted Answer

[3 2 1; 6 5 4]

Answer

`fliplr` flips the matrix left-to-right (reverses columns), producing [3 2 1; 6 5 4].

Question 4

What is the purpose of the backslash operator `A \ b` in MATLAB?

Accepted Answer

Solves the linear system Ax = b for x

Answer

`A \ b` uses Gaussian elimination to solve Ax = b, which is numerically preferred over `inv(A)*b`.

Question 5

How do you concatenate two matrices A (3×2) and B (3×3) horizontally in MATLAB?

Accepted Answer

[A, B]

Answer

`[A, B]` or equivalently `horzcat(A, B)` concatenates matrices side by side, requiring the same number of rows.

MATLAB - MATLAB Technical Computing Practice Test