MATLAB Variables and Workspace Interaction 4

Question 1

What does the `-v7.3` flag do in the `save` command?

Accepted Answer

Enables saving variables larger than 2 GB using HDF5 format

Answer

The `-v7.3` flag saves in HDF5-based format, which supports variables exceeding 2 GB, unlike the default format.

Question 2

How do you capture the contents of a .mat file into a struct without polluting the workspace?

Accepted Answer

s = load('file.mat')

Answer

When `load` is called with an output argument in function syntax, it returns a struct whose fields correspond to the saved variables.

Question 3

What is the class of a variable created by `x = 5` in MATLAB by default?

Accepted Answer

double

Answer

Numeric literals in MATLAB default to `double` (64-bit floating-point) unless explicitly cast to another type.

Question 4

Which function returns the number of bytes a variable occupies in memory?

Accepted Answer

whos('x') — check Bytes column

Answer

`whos` displays the bytes column for each variable; programmatically, `s = whos('x'); s.bytes` gives the byte count.

Question 5

What is the effect of suppressing output with a semicolon on a variable assignment like `x = 10;`?

Accepted Answer

The variable is stored but not printed to the Command Window

Answer

A trailing semicolon suppresses the echo of the assignment to the Command Window but the variable is still created in the workspace.

MATLAB - MATLAB Technical Computing Practice Test