MATLAB:Please Help with My Fixed Point Iteration Program

Hi all, I am trying to write a Fixed Point Iteration program but when I enter in the command line it kept giving me an error message. Can you please look over my program and tell me what might have gone wrong? Thank you very much!

First, I defined a function in a new M-File:

function y=FUN3(x)

y=5/(sin(x)*exp(-x./2));

Then, I opened up another M-File and wrote the program:

function Xs = FixedIterationRoot3(FUN3,Xest,imax)

syms x FUN3 FunDer3

Xi(1)=Xest;

FUN3=5/(sin(x)*exp(-x./2));

FunDer3 = diff(FUN3) % To find g'(x)

if abs(subs(FunDer3,x,Xest))>=1 % to check if g'(x) diverges

return;

fprintf('not valid')

end

for i=2:imax

Xi(i)=feval(FUN3,Xest);

Xest=Xi(i);

Xs=Xi;

end

When I enter in the command line:

>> xSolutions=FixedIterationRoot3('FUN3',-3,10)

it gave me error message:

syms x FUN3 FunDer3

??? Output argument "Xs" (and maybe others) not assigned during call

to

"C:\Users\Jane\Documents\MATLAB\FixedIterationRoot 3.m>FixedIterationRoot3".

Can you please help me fix something that is wrong or suggest an alternate method for Fixed Point Iteration?

I GREATLY APPRECIATE YOUR TIME!