Re: [Outer [Times, , ] ] Question

*To*: mathgroup at smc.vnet.net*Subject*: [mg45834] Re: [Outer [Times, , ] ] Question*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Tue, 27 Jan 2004 04:50:28 -0500 (EST)*Organization*: Universitaet Leipzig*References*: <bv00aa$jda$1@smc.vnet.net>*Reply-to*: kuska at informatik.uni-leipzig.de*Sender*: owner-wri-mathgroup at wolfram.com

Hi, remove the MatrixForm[], MatrixForm[] is a format function that wrap around your expression and hinder Plus[] to work as expected. Regards Jens MichaelSMcCain at cs.com wrote: > > Hi: > > I want to take a Column Vector and multiply it by a Row Vector to create an > "Outer" Matrix. > > In other words, I want to take a 5x1 Column Vector and multiply it by a 1x4 > Row Vector and output a 5x4 Matrix. > > I then want to add several of these Matrices together and obtain a "final" > Matrix. > > I tried the following: > > x1 = {1, -1, -1, 1, 1}; > y1 = {1, 1, -1, -1}; > > x2 = {-1, 1, -1, 1, -1}; > y2 = {1, -1, 1, -1}; > > x3 = {1, 1, -1, -1, 1}; > y3 = {-1, -1, 1, 1}; > > m1 = MatrixForm[Outer [Times, x1, y1] ] > m2 = MatrixForm[Outer [Times, x2, y2] ] > m3 = MatrixForm[Outer [Times, x3, y3] ] > > mm = m1 + m2 + m3 > > MatrixForm[mm] > > The output that I get is incorrect and does not combine into a single Matrix. > > What am I doing wrong? > > Thanks, > > Mike McCain > MichaelSMcCain at cs.com