[Octave-bug-tracker] [bug #45484] mldivide/mrdivide crashes octave 4 on windows, triggers exception on Linux and MacOSX

[Alois Schlögl]

URL:
  <http://savannah.gnu.org/bugs/?45484>

                 Summary: mldivide/mrdivide crashes octave 4 on windows,
triggers exception on Linux and MacOSX
                 Project: GNU Octave
            Submitted by: schloegl
            Submitted on: Mon 06 Jul 2015 08:27:35 PM GMT
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Crash
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 4.0.0
        Operating System: Microsoft Windows

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Details:


The following commands crash octave 4 on windows 7. 

  x=repmat(NaN,4); x/x
  x=repmat(NaN,4); xx
  mldivide(x,x)
  mrdivide(x,x)


The binary download 
 https://ftp.gnu.org/gnu/octave/windows/octave-4.0.0_0-installer.exe
was used. 

The same commands cause an exception on Octave 3.8.2 and 4.0 on Linux
(compiled from source on debian 8), as well as in MacOSX/homebrew. 

octave:1>   x=repmat(NaN,4); y=x/x
warning: matrix singular to machine precision, rcond = nan
 ** On entry to DLASCL parameter number  4 had an illegal value
error: exception encountered in Fortran subroutine dgelsd_
octave:1>   x=repmat(NaN,4); y=xx
warning: matrix singular to machine precision, rcond = nan
 ** On entry to DLASCL parameter number  4 had an illegal value
error: exception encountered in Fortran subroutine dgelsd_
octave:1>   y=mldivide(x,x)
warning: matrix singular to machine precision, rcond = nan
 ** On entry to DLASCL parameter number  4 had an illegal value
error: mldivide: exception encountered in Fortran subroutine dgelsd_
octave:1>   y=mrdivide(x,x)
warning: matrix singular to machine precision, rcond = nan
 ** On entry to DLASCL parameter number  4 had an illegal value
error: mrdivide: exception encountered in Fortran subroutine dgelsd_

and the result is undefined. 

I'd expect that no exception is triggered, but a result should be a matrix of
proper size as the following:


y =
   NaN   NaN   NaN   NaN
   NaN   NaN   NaN   NaN
   NaN   NaN   NaN   NaN
   NaN   NaN   NaN   NaN


That's what Matlab is providing. 

  Alois 





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