RE: [Lapackpp-devel] Tested LaLinearSolve(LaGenMatDouble, LaGenMatDouble &, LaGenMatDouble) ?

[Jacob \(Jack\) G. <jg...@cs...>]

I'll look into it some more later today when I get a chance, keep in mind
that the code runs differently for square matrices (calls the
LaLULinearSolve function) vs non-square matrices (calls the
LaQRLinearSolve).

I remember that my resulting matrix, X, only had values in the leftmost
column, and all were in the order of 10^-306 (I've never seen such small
numbers in my life :) ) when matlab's \ operator gave be good results.  I'll
try the same thing with complex matrices to see what happens, maybe I'm
doing something wrong.

Jack

-----Original Message-----
From: Christian Stimming [mailto:sti...@tu...] 
Sent: Tuesday, August 10, 2004 4:09 AM
To: Jacob (Jack) Gryn
Cc: lap...@li...
Subject: Re: [Lapackpp-devel] Tested LaLinearSolve(LaGenMatDouble,
LaGenMatDouble &, LaGenMatDouble) ?

Hi,

Jacob (Jack) Gryn schrieb:
> ps. if you haven't noticed, I posted the row-order changes to cvs last 
> night.

Yes, thanks a lot. This looks very nice. I have noticed and I also added 
some more documentation in the header.

 > I've been trying to solve a matrix equation Ax=b with all 3 variables,
 > A,x, and b, being LaGenMatDoubles.
 >
 > I've used tried the function LaLinearSolve(LaGenMatDouble,
 > LaGenMatDouble &, LaGenMatDouble), however, my results are clearly not
 > correct.  (Maybe I'm doing something wrong)
 >
 > Has this been tested?  I've noticed the tGenSolve.cc program does not
 > contain a test for the linear solve of 3 matricies.

I did not test the real-valued functions at all since I only use the 
complex-valued matrices and functions. It may very well be that there is 
some kind of bug. However, I would be quite surprised if this is the 
case since the linear solve routines really do not contain any 
non-trivial operations. Could you document the problem further? I know 
for sure the LaLinearSolve with LaGenMatComplex works correct, either 
for vectors or for matrices. Can you try for X and B vectors and then 
for some simple matrices? Maybe you could post a simple example (3x3) here?

Christian