I want to ask for a function f (X) with the command "INPUT" ... then create the function F1 = f(i*X).

example: f(X)=1/(1+0.2*X+5*X^2) => F1(X)=1/(1+0.2*i*X+5*(i*X)^2)

EXPORT test()

BEGIN

LOCAL f;

IF INPUT(f,"ENTER f with single quote. Example: '1/X' ") THEN

F1:=subst(f,X,'(i*X)');

END;

END;

I try :

F1:=expr("subst(f,'X','(i*X)')");

with another local var g :

g:=subst(f,X,'(i*X)');

F1:=g;

or :

CAS("F1:=subst(f,X,'(i*X)')");

I try also with string and the command REPLACE See my previous post...

I do not see it very clear... Thanks for your help.