3/8 Simpson's Rule

I created my code for 3/8 Simpson's Rule also ı want to add relative error. How can I add relative error in code.

function hasan2 (n)

a   = 0;
b   = 1;
h   = (b-a)/n;
sum = 0;
for i = 1:n-1
    a = (i-1)*h;
    b = i*h;
    sum = sum + 3/8*(f(a) + 3*f((2*a+b)/3) + 3*f((a+2*b)/3) + f(b));
end
    sum
end
function fx=f(x)

fx=exp(2*x)*sin(5*x);
end

Answer 1

[Alan Stevens]

The result of integrating of your function between 0 and 1 is:

I = (exp(1)^2*(2*sin(5)-5*cos(5)) + 5)/29;

so relative error is

relerror = abs(sum/I - 1);

As an aside, "sum" is a built-in Matlab function, so it's best not to use it as a variable name.