Re: Mathematica bug??
- To: mathgroup at smc.vnet.net
- Subject: [mg100575] Re: [mg100540] Mathematica bug??
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Mon, 8 Jun 2009 02:08:20 -0400 (EDT)
- Reply-to: hanlonr at cox.net
$Version
7.0 for Mac OS X x86 (64-bit) (February 19, 2009)
mat = {{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]]}};
inv = mat // Inverse
{{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}}
mat == (inv // Inverse)
True
Bob Hanlon
---- oshaughn <oshaughn 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?