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chdthanh

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04-05-2011
06:49 PM

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position of Zero pivot in Error -4 as using Pardiso ?

I have an error -4 whenusing pardiso to solve a sytem of linear equations. It may be caused by zero pivots. I wonder if I can know position of the zero pivots?

Thanks in advance.

Thanh

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Sergey_P_Intel2

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04-05-2011
11:58 PM

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For matrix types 2 and 4 you canknow the position of first zero pivot from iparm(30), please see MKL manual for details:

iparm(30) - the number of equation where PARDISO detects zero or negative pivot for MTYPE=2 (real positive definite matrix) and MTYPE=4 (complex and Hermitian positive definite matrices). If the solver detects a zero or negative pivot for these matrix types, the factorization is stopped, PARDISO returns immediately with an error (error = -4) and iparm(30) contains the number of the equation where the first zero or negative pivot is detected.

Regards,

Sergey

chdthanh

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04-06-2011
02:57 AM

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Thank for your reply. The value of iparm(30) is zero but I a still goterror=-4 for mtype=2.

I am using Intel MKL 10.0.3.

Could you please let me know what is problem ? How can I fix it?

Thank you in advance.

Thanh

Sergey_P_Intel2

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04-06-2011
04:41 AM

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Thanh,

This functionality was implemented in MKL since version 10.2 Gold (10.2.0).

Regards,

Sergey

This functionality was implemented in MKL since version 10.2 Gold (10.2.0).

Regards,

Sergey

chdthanh

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04-06-2011
04:54 AM

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I am using Interl fortran 10.1.021 which includes MKL 10.0.3.

Thanh

Gennady_F_Intel

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04-06-2011
06:23 AM

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Please have a look at this article. That's about how upgrade the obsolete version.

chdthanh

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04-06-2011
07:38 AM

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Many thanks to you. I know what I do now.

Thanh

Thanh

Danesh_Daroui

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04-07-2011
08:04 AM

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Why you get zero pivot error? try turning on matching and scaling. Using these two features in complex and unsymmetric matrices it will never be any zero in pivot but I am not sure if it works for other types. You can also re-generate the error in a small enough problem and try to solve it using LAPACK and see if LAPAKC's direct solver can solver it (non singular system). Some people think that highly ill-conditioned systems can not be solved using PARDISO and that confused me a lot but that's not true!

D.

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