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Re: Transpose[A]*A wrong?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg41151] Re: Transpose[A]*A wrong?
  • From: bobhanlon at aol.com (Bob Hanlon)
  • Date: Tue, 6 May 2003 05:55:51 -0400 (EDT)
  • References: <b950vl$r49$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Presumably you want the Dot product

Transpose[A].A


Bob Hanlon

In article <b950vl$r49$1 at smc.vnet.net>, "Daniel Lidström"
<daniel.lidstrom at _DELETE_home.se> wrote:

<< Subject:	Transpose[A]*A wrong?
From:		"Daniel Lidström" <daniel.lidstrom at _DELETE_home.se>
To: mathgroup at smc.vnet.net
Date:		Mon, 5 May 2003 06:39:49 +0000 (UTC)

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. >><BR><BR>


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