RE: Re: Possible Bug in Mathematica 6

*To*: mathgroup at smc.vnet.net*Subject*: [mg90230] RE: [mg90195] Re: Possible Bug in Mathematica 6*From*: "Amir Ahmed Ansari" <aansari at softpak.com>*Date*: Wed, 2 Jul 2008 06:38:09 -0400 (EDT)*References*: <g4d31k$et0$1@smc.vnet.net> <200807020928.FAA09861@smc.vnet.net>

Thanks everyone, especially Jean-Marc Gulliet for all the help. It seems I actually had the theorem wrong. Instead of using minors (which are many and can be obtained by deleting many different rows and columns), I was deleting only the first and last rows and consecutive columns (instead of disparate columns). Thanks again for the help. Best, - Amir -----Original Message----- From: Fabian [mailto:NOSPAM_fahasch at yahoo.de] Sent: Wednesday, July 02, 2008 2:29 PM To: mathgroup at smc.vnet.net Subject: [mg90230] [mg90195] Re: Possible Bug in Mathematica 6 On Tue, 1 Jul 2008 11:05:24 +0000 (UTC), Amir Ahmed Ansari <aansari at softpak.com> 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? Hm, do you mean that all 5x5 submatrices have a determinant equal to 0? Check Minors[matrix,5]

**References**:**Re: Possible Bug in Mathematica 6***From:*Fabian <NOSPAM_fahasch@yahoo.de>