I am not able to get the answer for the following code, I am using golden search section method.

%defining interval and function
function y = gss(func,x)
y = 6*x^2+11*x-35
xL = input('Enter the lower bound value = ');
xU = input('Enter the upper bound value = ');
%evaluating the function at end points
fL = func(xL);
fU = func(xU);
%calculating intermidiate point
R = 0.5*(sqrt(5)-1);
d = R*(xU-xL);
x1 = xU-d;
x2 = xL+d;
%evaluate function at x1 and x2
f1 = func(x1);
f2 = func(x2);
%main loop
tol = 1e-4;
err = inf;
while err > tol
    if f1 > f2
        xU = x2;                    %moving upper bound to x2
        fU = f2;
        x2 = x1;                    %new x2
        f2 = f1;
        d = R*(xU-xL);              %new x1
        x1 = xU-d;
        f1 = func(x1);              %evaluating f1
    elseif f1 < f2
        xL = x1;                    %moving the lower bound to x1
        fL = f2;
        x1 = x2;                    %new x1
        f2 = f1;
        d = R*(xU-xL);              %new x2
        x2 = xL+d;
        f2 = func(x2);              %evaluating f2
    else
        xL = (x1+x2)/2;
        xU = xL;
    end
    err = 2*abs(xU-xL)/(xU+xL);     %to determine if converged
end
%calculating final answer
xe = (x1+x2)/2
end

[SL: formatted the code as code not text]

Answer 1

[Steven Lord]

You define a function named gss but you never call that function.

Also, I would remove the first three lines of your code.

clc
close all
clear all

[Suchita Gupta]

how do i call it can you explain

[Torsten]

I recommend

https://de.mathworks.com/learn/tutorials/matlab-onramp.html