Matrix operation

*To*: mathgroup at smc.vnet.net*Subject*: [mg125753] Matrix operation*From*: Andrey Demidov <andrey.demidov at gmail.com>*Date*: Sat, 31 Mar 2012 03:45:04 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com

Hi, I have a matrix: >> s1 = {{0, 4, 3, 6, 1, 0, 0, 30}, {0, 6, 16, 8, 0, 1, 0, 256}, {0, 4, 1, 10, 0, 0, 1, 9}, {1, -2, -4, -3, 0, 0, 0, 0}} >> MatrixForm[s1] Now, I need to get another matrix (s2) where: - s2[i, j] = s1[i, j] where i <> 4 - s2[i, j] = s1[i, j] + 4 * s1[i - 1, j] where i == 4 What is the best way to get s2 ?