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Re: Mathematica bug??

  • To: mathgroup at smc.vnet.net
  • Subject: [mg100561] Re: Mathematica bug??
  • From: "Sjoerd C. de Vries" <sjoerd.c.devries at gmail.com>
  • Date: Mon, 8 Jun 2009 02:05:46 -0400 (EDT)
  • References: <h0fvlb$rct$1@smc.vnet.net>

I get a different answer:

{{1/Sqrt[1 - 2/r], 0, 0, 0}, {0, Sqrt[1 - 2/r], 0, 0}, {0, 0, 1/r,
  0}, {0, 0, 0, Csc[\[Theta]]/r}}

This is the correct answer. What version of Mathematica were you
using? Have you tried this on a fresh kernel?

Cheers -- Sjoerd

 On Jun 7, 11:01 am, oshaughn <oshau... at gravity.psu.edu> wrote:
> {{Sqrt[1 - 2/r], 0, 0, 0}, {0, 1/Sqrt[1 - 2/r], 0, 0}, {0, 0, r,
>    0}, {0, 0, 0, r Sin[\[Theta]]}} // Inverse
>
> gives
>
> {{0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 1/r, 0}, {0, 0, 0, Csc[\[Theta]]/
>   r}}
>
> with no warnings.  This is a *diagonal* matrix that should be
> trivially invertible.
>
> Does anyone know why Inverse has catastrophically failed here?



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