Re: Mathematica bug??

*To*: mathgroup at smc.vnet.net*Subject*: [mg100552] Re: [mg100540] Mathematica bug??*From*: Murray Eisenberg <murray at math.umass.edu>*Date*: Mon, 8 Jun 2009 02:04:06 -0400 (EDT)*Organization*: Mathematics & Statistics, Univ. of Mass./Amherst*References*: <200906070902.FAA28100@smc.vnet.net>*Reply-to*: murray at math.umass.edu

First, you should be very cautious about categorically, and so dramatically, entitling a post as "Mathematica bug". Second, such a title is so general as to be unhelpful to potential readers. Third, you don't say which version of Mathematica you're using. I tried this in Mathematica 7.0.1 and got the correct inverse: {{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 // InputForm {{1/Sqrt[1 - 2/r], 0, 0, 0}, {0, Sqrt[1 - 2/r], 0, 0}, {0, 0, r^(-1), 0}, {0, 0, 0, Csc[\[Theta]]/r}} But then I also tried it in Mathematica 5.2, and still I got the correct inverse. I suspect you had already assigned a value to r or Theta somewhere earlier in the evaluation steps. Or else just mistyped something. oshaughn 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? > -- Murray Eisenberg murray at math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 549-1020 (H) University of Massachusetts 413 545-2859 (W) 710 North Pleasant Street fax 413 545-1801 Amherst, MA 01003-9305

**References**:**Mathematica bug??***From:*oshaughn <oshaughn@gravity.psu.edu>