How to save variables in MATLAB function in the workspace

Good day.

I have a MATLAB function which I run from a script. I want to plot some variables in the function from my script so I want to save these variables in my workspace. Is there any way to do it other than using them as an output to the function when I call it from the script? The variables are many so I am trying to avoid too many output arguments.

Thanks now and always.

[Stephen23]

Messing around with assignin or lots of output variables is not a good approach.

Just assign the variables to fields of a structure and return that. Simple.

Answer 1

[Robin Kirsch]

Use assignin command

function y = test()

assignin('base','x',42)

y = 0

end

[ojonugwa adukwu]

Thanks. But this assignin assumes the variables are in the workspace already I guess? What I want is that the variables in the function can be read from the script meaning, they appear on the workspace where I can plot them from.

Thanks.

[Robin Kirsch]

assignin('base','x',42) will create a variable x in the base workspace and fill it with the number 42.

[Robin Kirsch]

the workspace can be empty and it will save it to it

[Robin Kirsch]

this works only if you run your function first and then run your script to plot the variables of course

Answer 2

[Cris LaPierre]

You could save them to a mat file. When you want to plot them, load the mat file in your script.

You could also consider placing the variables in a structure. That way, your function only needs to have one output, yet all the variables can be passed out.

[ojonugwa adukwu]

Thanks Bro.

But this safe to mat file assumes the variables are in the workspace already I guess? What I want is that the variables in the function can be read from the script meaning, they appear on the workspace where I can plot them from.

Thanks.

[Cris LaPierre]

You'd have to run the save command from inside your function.

[ojonugwa adukwu]

Thanks.

I did. I wrote save (gas) after last line in my fucntion but I got an error message that "Undefined function or variable 'gas'.". Is there anything I need to do again?

Many thanks.

[Cris LaPierre]

Look at the syntax in the link I shared. When using parentheses, you need to put your filename in quotes. Either of the following syntaxes should work:

save('gas.mat')

or

save gas.mat

I guess you don't technically need to include the extension, but it's recommended.

[ojonugwa adukwu]

Thanks so much Cris.

This looks promising to work. The issue now is the length of time it takes. For example, I have not completed one simulation cycle for a program that has 150 simulation cycle. I even used a variable that is a scalar here yet I waited for over an hour without completing one simulation cycle.

[Cris LaPierre]

Hard to say without seeing your code.

[ojonugwa adukwu]

Yea. My codes are lengthy. A script and four functions. But I have resolve it using the idea proposed by

Stephen Cobeldick (assignin). It takes time but it ok for me until I get a better one.

Many thanks for everything.

[Cris LaPierre]

Just to clarify, that wasn't Stephen's suggestion. His recommendation was NOT to do that. He suggested using a structure, as did I. That would likely be the quickest approach since you don't have to write the variables to the workspace or the harddrive.

[ojonugwa adukwu]

Sorry. I meant Robin Kirsch. The "assignin" he suggested is slow but it is faster than the process of saving to matfile. I really do not know why that has been extremely slow for me. Hopefully I will get to know why.

Thanks so much