quad2dggen

error:  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).