MATLAB Variables and Workspace Interaction Questions and Answers

Question 1

Which of the following is an invalid variable name in MATLAB?

Accepted Answer

_var

Answer

MATLAB variable names must begin with a letter, followed by letters, digits, or underscores. A variable name cannot start with an underscore.

Question 2

A user has several variables in the workspace: `price_usd`, `price_eur`, `tax_rate`, and `quantity`. Which command would save only the variables related to price into a file named `prices.mat`?

Accepted Answer

save('prices.mat', 'price*')

Answer

The `save` function can use a wildcard character (*) to save variables that match a specific pattern. The command `save('prices.mat', 'price*')` correctly saves all variables whose names start with 'price'.

Question 3

What is the key difference between the `who` and `whos` commands?

Accepted Answer

`who` only lists variable names, while `whos` provides detailed information like size, bytes, and class.

Answer

The `who` command displays a simple list of the variables currently in the workspace. The `whos` command provides a more detailed list that includes the name, size, number of bytes, class, and other attributes for each variable.

Question 4

If the workspace contains a variable `x = 10`, and you execute the command `load('my_data.mat')`, where `my_data.mat` also contains a variable named `x` with the value `50`, what will be the state of the workspace variable `x` after the command completes?

Accepted Answer

The value of `x` will be overwritten and become `50`.

Answer

When you load variables from a MAT-file, if a variable in the file has the same name as a variable already in the workspace, the `load` function will overwrite the existing variable with the one from the file.

Question 5

What is the primary characteristic of a `persistent` variable in a MATLAB function?

Accepted Answer

Its value is retained in memory between calls to the function.

Answer

A persistent variable is local to the function in which it is declared, but its value is preserved in memory between calls to that function. Unlike global variables, it cannot be accessed from outside the function.

MATLAB - MATLAB Technical Computing Practice Test

MATLAB - MATLAB Technical Computing Practice Test

MATLAB Variables and Workspace Interaction Questions and Answers