RE: Matrix Multiplication (with a twist)

*To*: mathgroup at smc.vnet.net*Subject*: [mg69004] RE: [mg68951] Matrix Multiplication (with a twist)*From*: "David Park" <djmp at earthlink.net>*Date*: Sat, 26 Aug 2006 02:04:50 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Bruce, Use NonCommutativeMultiply and Inner. A = {{e, f}, {g, h}}; B = {{a, b}, {c, d}}; Inner[#1 ** #2 &, A, B] {{e ** a + f ** c, e ** b + f ** d}, {g ** a + h ** c, g ** b + h ** d}} David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ From: Bruce Colletti [mailto:vze269bv at verizon.net] To: mathgroup at smc.vnet.net For matrix A = {{e,f},{g,h}} and B = {{a,b},{c,d}}, Mathematica returns their product A.B = {{ae+cf,be+df},{ag+ch,bg+dh}} However, I want to treat multiplication of numeric variables as noncommutative in order to instead obtain the result {{ea+fc, eb+fd},{ga+hc,gb+hd}} How would this be done in v5.2? Thanks. Bruce