3D Simpson's Integrator

Fast, fully vectorised version of the Simpson's method for 3D domains. This code avoids the use of any for loops etc. For a given level of accuracy it can be an order of magnitude or more faster than triplequad.

Examples are provided within the code.

Useage:

ans = simp3D('func3D',xs,xe,ys,ye,zs,ze,NX,NY,NZ)

Input parameters:

func3D - 3D function that accepts vector inputs (otherwise
misleading results can occur)

xs, xe - x-limits of integration
ys, ye - y-limits of integration
zs, ze - z-limits of integration

NX - number of integration intervals in the x-direction (should be even)
NY - number of integration intervals in the y-direction (should be even)
NZ - number of integration intervals in the z-direction (should be even)