Error on minimize?

Now, I’m working with CVX on matlab

I have code following:

variable x(n)
minimize( norm(A*x-b) )

I want to write: minimize(norm(f(x))) stead of minimize( norm(Ax-b) ) where f(x) = Ax-b
But, It’s error.
please, help me !!

You can declare Fx as an expression

expression fx

fx = Ax-b

You haven’t given us any information at all about what f is, or what the error message is that you are receiving.

Thank Jelena very much!

But, I want to fx is file other (not in main.m). Please help me!

I’m going to close this one since you’ve apparently posted a new one with more information.