ListCorrelate[] ??

*To*: mathgroup at smc.vnet.net*Subject*: [mg30104] ListCorrelate[] ??*From*: Brent Pedersen <bpederse at nature.berkeley.edu>*Date*: Sat, 28 Jul 2001 01:51:04 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

with a real square matrix H, I calculate the sum of each cell and its 8 neighbors as: Htot=ListCorrelate[kern, H ,{2,-2}]; (thanks to the help of some of you) where: kern = Table[1, {3}, {3}]; now, for each 9 cell neighborhood around (and including cell H[[i,j]], I wish to calculate: Sum[(H[[m,n]]/Htot[[i,j]])^c,{m,i-1,i+1},{n,j-1,j+1}]; (when c=1, this will be 1.) of course, this code won't work as is but the idea is there.I can write loops containing a Sum[] similar to that above,but i am sure that ListCorrelate[] operates much faster (which is important since H is 256*256).in short, i need to output a 256*256 matrix where each cell contains the result of the Sum[] function above. ListCorrelate[kern, H/Htot,{2,-2}]; does not work because it contains H[[i,j]]/Htot[[i,j]] not H[[i,j]]/Htot[[m,n]]; will some variation of ListCorrelate[H, 1/Htot, {n,-n}]; work? as yet, no luck with that. any ideas will be greatly appreciated. thanks, -brent

**Follow-Ups**:**Re: ListCorrelate[] ??***From:*Daniel Lichtblau <danl@wolfram.com>