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RE: Re: Possible Bug in Mathematica 6

• To: mathgroup at smc.vnet.net
• Subject: [mg90229] RE: [mg90191] Re: Possible Bug in Mathematica 6
• From: "Amir Ahmed Ansari" <aansari at softpak.com>
• Date: Wed, 2 Jul 2008 06:37:58 -0400 (EDT)
• References: <g4d31k$et0$1@smc.vnet.net> <200807020927.FAA09812@smc.vnet.net>

Nopes see my follow up on the list and the corrections performed by
Jean-Marc Gulliet. f_11 is really just f11, I am using latex notation to
denote subscripts. So no; we are not dealing with lists. And non-square
matrices don't have a determinant :-)

-----Original Message-----
From: Jens-Peer Kuska [mailto:kuska at informatik.uni-leipzig.de] 
Sent: Wednesday, July 02, 2008 2:28 PM
To: mathgroup at smc.vnet.net
Subject: [mg90229] [mg90191] Re: Possible Bug in Mathematica 6

Hi,

f_11 is a *pattern* with a invalid head ?? You mean f[1,1] ??
and a 9 x 6 matrix (non square) has always  a zero determinant.

Regards
   Jens

Amir Ahmed Ansari wrote:
> Hi,
> 
> I tried this on a friend=92s computer using Mathematica 6. Consider the
> following matrix:
> 
> {
>     { f_11, f_12, f_13, 0, 0, 0, 0, 0, 0 },
>     { 0, 0, 0, f_21, f_22, f_23, 0, 0, 0 },
>     { 0, 0, 0, 0, 0, 0, ( a f_11 + b f_21 ), ( a f_12 + b f_22 ), =
> ( a f_13 +
> b f_23 ) },
>     { f_21, f_22, f_23, f_11, f_12, f_13, 0, 0, 0 },
>     { ( a f_11 + b f_21 ), ( a f_12 + b f_22 ), ( a f_13 + b f_23 =
> ), 0, 0,
> 0, f_11, f_12, f_13 },
>     { 0, 0, 0, ( a f_11 + b f_21 ), ( a f_12 + b f_22 ), ( a f_13 =
> + b f_23
> ), f_21, f_22, f_23 }
> }
> 
> 
> All 5x5 have a determinant of 0 as can be seen by using Det[]. Yet,
> MatrixRank[] comes out to be 5. Is this a bug or am I doing something
> stupid?
> 
> 
> 

• References:
  • Re: Possible Bug in Mathematica 6
    • From: Jens-Peer Kuska <kuska@informatik.uni-leipzig.de>