Issue with CAS solver function involving passing strings to the variable position.

[Gene222]

I don't know how to get SOLVE or fsolve to solve your equation. Some comments on your first program are:
(1) Your choose variable A is the same as your variables[6] which is also defined as A.
(2) I tried using fsolve instead of SOLVE, but it gave {} which I think means fsolve could not find an answer for the initial guess.
(3) I tried exporting the solve variables, but that did not help.
Below are the changes I made to your program in trying to get the program to work. I predefined your list variables, because I got tired of inputting the values in the INPUT screen.
Sorry I could not help you.

PHP Code:

EXPORT Â,τ,ω,A1,Answer;
EXPORT Find,Find_1,variables;

export Amplitude()
BEGIN
print();

Â:=0.0355;
K:=5;
τ:=10;
ω:=3.1415;
E:=0.5;
A1:=7;


CHOOSE(A,"Which Amplitude?","Final","Initial");
if A==1 then
variables:={"Â","K","τ","ω","E","A1"};
input({{Find,variables,{56,15,0}},{Â,[0],{10,20,1}},{K,[0],{10,20,2}},{τ,[0],{10,20,3}},{ω,[0],{10,20,4}},{E,[0],{10,20,5}},{A1,[0],{10,20,6}}});
Find_1:=variables[Find]; Find:=Find_1;
Answer:=fsolve("Â=K*A/(sqrt((1-(τ*ω)^2)^2+(2*τ*ω*E)^2)),"+Find+"=1)");
print(Answer);
end;
END;