How to calculate gradient and laplace of a list

*To*: mathgroup at smc.vnet.net*Subject*: [mg72871] How to calculate gradient and laplace of a list*From*: "leoshen" <programrelated at gmail.com>*Date*: Tue, 23 Jan 2007 05:17:15 -0500 (EST)

Hi, guys I have a matrix of n*m read from a file. mathematica has built in function to do discrete fourier transform of the list. Can I calculate the gradient and the laplace of the matrix? I can use the listcontourplot to plot the matrix, Is there any way to plot the gradient plot of it?