Is the amount of hard drive space used when a variable is saved to a .mat file equivalent to the amount of RAM the variable requires when loaded into the workspace?

I am working on large, multidimensional images and recently got an error in R2017a for my variable being too large (~33GB when I only have 32GB of RAM). I made a slight adjustment to decrease the size of my array and everything worked as expected.

However, once I saved the variable as a .mat file I found that the file is quite a bit smaller, ~193MB.

Why is that the case, and will there be issues when I attempt to load the file into my workspace?

Answer 1

[Walter Roberson]

.mat -v7.3 files can use compression.