Variables and Workspace Interaction Flashcards

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

Answer: Enables saving variables larger than 2 GB using HDF5 format

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

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

Answer: s = load('file.mat')

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

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

Answer: double

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

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

Answer: whos('x') — check Bytes column

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

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

Answer: The variable is stored but not printed to the Command Window

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

Which of the following correctly declares a global variable in a MATLAB function?

Answer: global x; x = 5;

The `global` keyword must appear on its own declaration line before the variable is used; assignment follows separately.

What happens when you call `clear x` inside a function that has `x` declared as `persistent`?

Answer: The persistent value is erased

`clear x` inside the function clears the persistent variable `x`; to clear persistent variables from outside, you use `clear functionName`.