Approximate 2-D integral.
SOM=integ2d(MAT) SOM=integ2d(MAT,X) SOM=integ2d(MAT,X,Y)
MxN matrix to be integrated
N-row-vector indicating the abscissa integration path (default : 1:N)
M-column-vector indicating the ordinate integration path (default : 1:M)
result of integration
integ2d approximates the 2-D integral of matrix MAT according to abscissa X and ordinate Y.