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Re: Transpose[A]*A wrong?

• To: mathgroup at smc.vnet.net
• Subject: [mg41186] Re: [mg41129] Transpose[A]*A wrong?
• From: "German Buitrago A." <gerbual at col2.telecom.com.co>
• Date: Tue, 6 May 2003 06:06:15 -0400 (EDT)
• References: <200305050640.CAA27855@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

Damiel:

If what you attempt is to obtain the product of matrices, then use
Transpose[A].A  (or Dot[Transpose[A],A]) instead of Transpose[A]*A.

Germán Buitrago A.
Manizales, Colombia



----- Original Message -----
From: "Daniel Lidström" <daniel.lidstrom at _DELETE_home.se>
To: mathgroup at smc.vnet.net
Subject: [mg41186] [mg41129] Transpose[A]*A wrong?


> 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
>
>
>

• References:
  • Transpose[A]*A wrong?
    • From: "Daniel Lidström" <daniel.lidstrom@_DELETE_home.se>