Re: Combining Matrices

*To*: mathgroup at smc.vnet.net*Subject*: [mg65028] Re: [mg65017] Combining Matrices*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Sun, 12 Mar 2006 23:57:45 -0500 (EST)*Reply-to*: hanlonr at cox.net*Sender*: owner-wri-mathgroup at wolfram.com

n=3;p=4;q=2; A=Array[a,{n,p}]; B=Array[b,{n,q}]; X=Join@@@Thread[{A,B}] X=Join@@@Transpose[{A,B}] Needs["LinearAlgebra`MatrixManipulation`"]; X=AppendRows[A,B] Needs["Statistics`DataManipulation`"]; X=RowJoin[A,B] Bob Hanlon > > From: Gregory Lypny <gregory.lypny at videotron.ca> To: mathgroup at smc.vnet.net > Subject: [mg65028] [mg65017] Combining Matrices > > Hello Everyone, > > I'm trying to figure out how to combine an n x p matrix and an n x q > matrix to form an n x (p + q) matrix. I found one way, shown in the > second last line of the code below, but I have no idea why it works, > and I'm wondering whether there is a more direct way. The example > takes 3 x 4 matrix A and combines it with 3 x 2 matrix B to form 3 x > 6 matrix X. > > Any thoughts would be most appreciated. > > Gregory > > Clear[X] > n = 3; p = 4; q = 2; > A = Array[a, {n, p}]; > B = Array[b, {n, q}]; > (X = Transpose[Flatten[{{Transpose[A], Transpose[B]}}, 2]]) // > MatrixForm > Dimensions[X] > >