MATLAB Variables and Workspace Interaction 5

Question 1

What is the key difference between `global` and `persistent` variables in MATLAB?

Accepted Answer

Global variables are shared across functions that declare them global; persistent variables retain their value between calls within a single function

Answer

`global` shares a variable across any function that declares it global, while `persistent` retains a value between calls within one specific function.

Question 2

What does `inputname(n)` return inside a MATLAB function?

Accepted Answer

The name of the variable passed as the nth argument by the caller

Answer

`inputname(n)` returns a string containing the name of the variable the caller used for the nth argument, or empty if it was an expression.

Question 3

How can you list all variables in the workspace that match the pattern 'data*'?

Accepted Answer

Both A and B

Answer

Both `who data*` and `whos('data*')` accept wildcard patterns and list matching workspace variables.

Question 4

After running a script that sets `x = 42`, the variable `x` persists in the base workspace. Why?

Accepted Answer

Scripts share the base workspace; they do not create their own scope

Answer

Unlike functions, MATLAB scripts execute in the caller's (or base) workspace, so all variable assignments affect that shared scope.

Question 5

What does `evalin('base', 'x')` do?

Accepted Answer

Evaluates and returns the value of 'x' from the base workspace

Answer

`evalin('base', expr)` evaluates an expression string in the base workspace, allowing functions to read variables from the base scope.

MATLAB - MATLAB Technical Computing Practice Test

MATLAB - MATLAB Technical Computing Practice Test

MATLAB Variables and Workspace Interaction 5