Format of return value of user defined function

i was using this function below to evaluate a non linear equation with False Position Method. this function is working pretty well but the value it returns is NOT in long format.

for example if i use this function to solve the following non linear equation,

 f(x)=10-2.1*x-.01*x^3;
  a=4;b=5;

then i get

 z=50306586349162394761257938446687780/11523119672512394327137541804059681

how can i resolve this problem?

% this fuction evaluates the root of a equation with
% the use of False Position Method.
tol=1e-5;
FU=f(upper);
FL=f(lower);
while (abs(upper-lower)/upper)>tol
    x=lower-((FL*(upper-lower))/(FU-FL));
    FX=f(x);
    if(FX*FL<0)
        upper=x;
    elseif(FX*FU<0)
        lower=x;
    else
        break
    end

end
end

Answer 1

[Walter Roberson]

With difficulty. Your code does not assign anything to z and your code is not a function so we cannot guess that you assigned an output to z.

But mostly, do not use

   syms x
   f(x)=10-2.1*x-.01*x^3

Instead use

f = @(x) 10-2.1*x-.01*x^3

[Md Monirul Islam]

thanks a lot. it solved the problem.