The following is the code for evaluating a definite integral of a given function by a Numerical Method called Trapezoidal Rule.

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//Trapezoidal Rule
//Evaluates the definite integral of a function f(x), from a to b.
//Written By: Manas Sharma(www.bragitoff.com)
funcprot(0);
function ans=trapez(a, b, n, f)//function definition of simpson
h=(b-a)/n;
sum=0;
for i=1:n-1
x=a+i*h;
sum=sum+2*f(x);
end
ans=(h/2)*(f(a)+f(b)+sum);
endfunction

You can either copy the code above and save it as a .sci file or download the file . Once you run the code, the function ‘trapez(a,b,n,f)’ can be called by other programs or even in the console.

Function syntax:

trapez(a,b,n,f)

where,

a=initial limit(real no.)
b=final limit(real no.)
n=no. of sub-intervals(the higher the value of ‘n’ the better is the result.

Example:
The following code snippet evaluates the integral of 1/(1+x^2) from 0 to 2.

I'm a physicist specializing in theoretical, computational and experimental condensed matter physics. I like to develop Physics related apps and softwares from time to time. Can code in most of the popular languages. Like to share my knowledge in Physics and applications using this Blog and a YouTube channel.