Incorrect result of rcond with Netlib LAPACK

[Sébastien Villemot]

Hi,

I attach a MAT-file containing a 2x2 matrix (Finf), whose rcond is
different depending on the flavor of LAPACK that I use.

With Netlib LAPACK:

 octave:2> rcond(Finf)
 ans =  0.40463

With Atlas' LAPACK:

 octave:2> rcond(Finf)
 ans = 0

MATLAB gives 5.5511e-17.

Since the matrix is quasi-singular, the right answer is (almost) zero. A
value of 0.4 is plain wrong.

I cannot determine if this is a bug in Netlib LAPACK or Octave. I wrote
a C program reading the matrix with libmatio then calling dgetrf+dgecon
and I get the right result with both versions of LAPACK, so this points
towards a bug in Octave, but I am still unsure.

I am quite puzzled by this issue, so I would be happy to hear your
feedback.

Thanks,

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