How can I replace an expression in a symbolic function with a new symbolic variable?

Hello to everyone,

I am using the Symbolic Math Toolbox and, after some steps, I've obtained a very complex symbolic function f. In order to make it easier to read, I'd like to replace some terms of the function with new symbolic variables, but I don't know how.

For example, assuming that the f function is

f = sqrt(A^2 + A*B)

I want to replace the term A*B with a new symbolic variable C, so that

f = sqrt(A^2 + C)

How can I do that? Thanks in advance for your help.

Answer 1

[madhan ravi]

syms A B C

f = sqrt(A.^2+ A*B)

subs(f,A*B,C)

actually this works

[Savino Petrignani]

Thank you so much, it works.

[madhan ravi]

Anytime

Answer 2

[Basil C.]

I assume that this should be what you are looking for

function result= C(A,B)
  result=A*B;
end

But use this before the function f = sqrt(A^2 + C)

[Savino Petrignani]

Actually, I don't have in my code

f = sqrt(A^2 + C)

but only

f = sqrt(A^2 + A*B)

In my complex function, the same expression appears several times and so I need to replace this expression with a new symbolic variable.

[Basil C.]

So you mean to say you want to replace the function f ?