Question

I want to use instead of matlab integration command, a basic self created one. Do you have any Idea how to fix the error? If I use Matlab quad command, my algorithm works good but when I try to use my self created integral function,not suprisingly for sure, it does not work:(

M-File:

function y = trapapa(low, up, ints, fun)
 y = 0;
    step = (up - low) / ints;
    for j = low : step : up
        y = y + feval(fun,j);
    end
    y = (y - (feval(fun, low) + feval(fun, up))/2) * step;

Mean algorithm:

clear;
x0=linspace(0,4,3);
y=linspace(0,2,3);
for i=1:length(x0)
for j=1:length(y)
x(i,j)=y(j)+x0(i);
alpha=@(rho)((5-2*x(i,j)).*exp(y(j)-rho))./2;
%int(i,j)=quad(alpha,0,y(j))
int(i,j)=trapapa(alpha,0,y(j),10)
end
end

Answer 1

You are not following your function definition in the script. The fun parameter (variable alpha) is supposed to be the last one.

Try int(i,j)=trapapa(0,y(j),10,alpha)