inverse matrix

[Ólafur Jens Sigurðsson]

Hi

I came across the following scenario:
For the following matrix

 1.0634e-02   -7.5196e-03   -1.0610e-13   -4.4593e-04
-7.5196e-03    1.5066e-01    7.5071e-14   -2.5578e-03
-1.0610e-13    7.5071e-14
    1.7039e-04    4.4484e-15
-4.4593e-04   -2.5578e-03    4.4484e-15    1.8909e-04

the inverse in version 2.9.10 in debian produces rcond = 0 but in 2.1.73 it is rcond = 0.00065696

Does this happen in all machines or is this just me (a AMD Athlon 1344 MHz, cpu family 6, model 8 ... info taken from /proc/cpuinfo running debian unstable)?

If this is a general thing, is there a reason for why the 2.9.10 is worse in this then 2.1.73 (I would consider this to be worse, unless 2.1.73 is just doing wrong calculation).

Regards

Oli

ps, creat the matrix by the following command (set in so you can just cut and paste)

a = [1.2500e+02, 1.4595e+01, 5.8551e-08, 4.9222e+02; 1.4595e+01, 1.0320e+01, -2.2343e-12, 1.7402e+02; 5.8551e-08, -2.2343e-12, 5.8688e+03, -1.5056e-11; 4.9222e+02, 1.7402e+02, -1.5056e-11, 8.8034e+03]