usage: int = quad2dggen('Fun','funxlow','funxhigh',ylow,yhigh)
or
int = quad2dggen('Fun','funxlow','funxhigh',ylow,yhigh,tol)
This function is similar to QUAD or QUAD8 for 2-dimensional integration
over a general 2-dimensional region, but it uses a Gaussian quadrature
integration scheme.
The integral is like:
yhigh funxhigh(y)
int = Int Int Fun(x,y) dx dy
ylow funxlow(y)
int -- value of the integral
Fun -- Fun(x,y) (function to be integrated)
funxlow -- funxlow(y)
funxhigh-- funxhigh(y)
ylow -- lower y limit of integration
yhigh -- upper y limit of integration
tol -- tolerance parameter (optional)
Note that if there are discontinuities the region of integration
should be broken up into separate pieces. And if there are singularities,
a more appropriate integration quadrature should be used
(such as the Gauss-Chebyshev for a specific type of singularity).
