function [ret_counts, xbins, ybins] = hist2d(M,xbins,ybins)
DESCRIPTION
hist2d ([x,y], xbins, ybins, norm)
Produce a 2D histogram.
Points xi,yi are stored in a 2-column array.
If ybins is missing, use xbins.
If bins is a scalar, use that many bins.
If bins is a vector, it represents bin edges.
CROSS-REFERENCE INFORMATION
This function calls:
mesh % Plot a mesh given matrices @var{x}, and @var{y} from @code{meshgrid} and
