Calling another script file in MATLAB

I am having a problem with calling another script from within a script. I run a script "a.m" and it uses a function detailed in another script "b.m", and within开发者_开发技巧 "b.m" there is an if clause which is supposed to rerun "a.m" given a certain condition is fulfilled. However, when trying to write this if clause and calling "a.m", i get this error:

Undefined variable "a" or class "a.m".

% My "if" clause in b.m looks like this:
if numel(xyz) == 0
    a.m;
end

Why am I getting this error, considering it's "a.m" that I initially run?

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The syntax is wrong. You call it as a not a.m.