Numerical Integration using Simpson's Rules

Implementation based on the theory contained in "Numerical Methods for Engineers" by Steven C. Chapra.

Instructions to use the function

The user must provide the function as an anonymous function in the command window. This can be done by introducing

f=@(x) x.*exp(2*x)

Then, the user should invoke the function by indicating four parameters:

Simp(f,lmin,lmax,N)

where f is the integrand and N is the number of intervals. lmin and lmax are the lower and upper limits of the definitive integral.

The function automatically chooses the method to follow depending on the value of N.

- If N is an even number, it selects Simpson's rule 1/3
- If N is divisible by 3, it selects Simpson's rule 3/8
- In N is an odd number and not divisible by 3, it combines the methods.