From help-octave-request at bevo dot che dot wisc dot edu  Wed Dec  8 03:08:30 1999
Subject: Constructor for LU: why dgesv?
From: Thomas Hoffmann <hoffmann at ehmgs2 dot et dot tu-dresden dot de>
To: help-octave at bevo dot che dot wisc dot edu
Cc: hoffmann at ehmgs2 dot et dot tu-dresden dot de
Date: Wed, 8 Dec 1999 10:07:39 +0100 (MET)

Excuse my ignorance, but when looking into the ctor for LU (e.g. dbleLU.cc),
I noticed that octave calls the Fortran subroutine dgesv, with a second parameter
(NRHS) of 0. 

dgesv calls in turn DGETRF (factorization) and DGETRS (solution). 

But if one uses NRHS=0, DGETRS only checks some parameters and returns.

Why does the ctor not call dgetrf directly, when only the factorization is necessary?

Regards,
Thomas Hoffmann.


=============================================================================
Thomas Hoffmann, Institut fuer Halbleiter- und Mikrosystemtechnik, TU Dresden 
E-mail: hoffmann at ehmgs2 dot et dot tu-dresden dot de



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