[Octave-bug-tracker] [bug #46103] inversion of a singular diagonal matrix A produces inv(A)==A

[jan]

URL:
  <http://savannah.gnu.org/bugs/?46103>

                 Summary: inversion of a  singular diagonal matrix A  produces
 inv(A)==A  
                 Project: GNU Octave
            Submitted by: pfa
            Submitted on: fre  2 okt 2015 09.51.36
                Category: Libraries
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 4.0.0
        Operating System: GNU/Linux

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Details:


Inverting (with inv) a singular diagonal matrix results the 
matrix itself, but mrdivide and mldivide act correctly. 

This bug affects also at least version 3.8.2. (from ubuntu 15.04. packaging.)



>> version
ans = 4.0.0
>> w=diag(0:2); id=eye(3); inv(w), w\id, id/w
warning: matrix singular to machine precision, rcond = 1
ans =
Diagonal Matrix
   0   0   0
   0   1   0
   0   0   2
ans =
Diagonal Matrix
   0.00000         0         0
         0   1.00000         0
         0         0   0.50000
ans =
Diagonal Matrix
   0.00000         0         0
         0   1.00000         0
         0         0   0.50000
>>







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