Re: Transpose[A]*A wrong?
- To: mathgroup at smc.vnet.net
- Subject: [mg41165] Re: [mg41129] Transpose[A]*A wrong?
- From: Selwyn Hollis <selwynh at earthlink.net>
- Date: Tue, 6 May 2003 06:00:47 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Matrix multiplication is done with Dot. What you want is Transpose[A].A ----- Selwyn Hollis http://www.math.armstrong.edu/faculty/hollis On Monday, May 5, 2003, at 02:40 AM, Daniel Lidström wrote: > Hi, > > why does Mathematica give the wrong result here? > > In[1]:= \!\(A\ = \ {{x\_11, x\_12, x\_13}, {x\_21, x\_22, x\_23}, > {x\_31, > x\_32, > x\_33}}\) > > Out[1]= {{x , x , x }, {x , x , x }, {x , x , x }} > 11 12 13 21 22 23 31 32 33 > > In[2]:= Transpose[A]*A > > 2 2 > 2 > Out[2]= {{x , x x , x x }, {x x , x , x x }, {x x , > x x > , x }} > 11 12 21 13 31 12 21 22 23 32 13 31 > 23 > 32 33 > > Look at the diagonal elements for example. > Thanks! > > /Daniel > > -- > > Daniel Lidström > > 62 23' 25" N > 17 15' 31" E > > > >