Re: [Outer [Times, , ] ] Question

*To*: mathgroup at smc.vnet.net*Subject*: [mg45817] Re: [Outer [Times, , ] ] Question*From*: Oleksandr Pavlyk <pavlyk at phys.psu.edu>*Date*: Mon, 26 Jan 2004 01:53:20 -0500 (EST)*Organization*: Penn State University, Center for Academic Computing*References*: <bv00aa$jda$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hi, You need to get rid of MatrixForm when assigning m1, m2, m3: {m1,m2,m3} = MapThread[ Outer[Times, #1, #2] & , {{x1, x2, x3}, {y1, y2, y3}} ]; MatrixForm[ Plus @@ {m1,m2,m3} ] Sasha 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 >