Re: How to calculate gradient and laplace of a list

*To*: mathgroup at smc.vnet.net*Subject*: [mg72902] Re: How to calculate gradient and laplace of a list*From*: dh <dh at metrohm.ch>*Date*: Wed, 24 Jan 2007 17:37:36 -0500 (EST)*References*: <ep4kd5$rat$1@smc.vnet.net>

Hi, you can do this using ListCorrelate or ListConvolve. For ListCorelate the Kernel would be: x component of Gradient: ker={{0,0,0},{-1,0,1},{0,0,0}}/2 y component of Gradient: ker={{0,1,0},{0,0,0},{0,-1,0}}/2 Laplacian: ker={{0,1,0},{1,-4,1},{0,1,0}}/4 you would then write: ListCorrelate[ker,matrix] To plot you can use: ListPlotVectorField from: Graphics`PlotField`. But you first have to prepare the data. Assume that gradx and grady are matrixes with the corresponding components, then the gradient matrix is: grad=Transpose[{gradx, grady}, {3, 1, 2}] and we get a Plot by: <<Graphics`PlotField` ListPlotVectorField[grad] Daniel leoshen wrote: > 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? > > > >