Re: [Lapackpp-devel] Error in LaGenMatDouble::copy(...) and other questions

[Christian S. <sti...@tu...>]

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Dominik Wagenfuehr schrieb:
>> That's a serious error. I have spent a lot of checking on the
>> LaGenMatDouble methods, including the ::copy() method. If you can
>> extrace the relevant code portion than that would be really helpful.
> 
> Ok, the program crashed at LaGenMatDouble but the error is in sybfd.h in
> the factorize-function I have called earlier. I have fixed it and will
> send you a new file with documentation later (see at the end).

Thanks. Looking forward to this.

>> Again, this isn't "my fault" :-) because this code has been untouched
>> from the original lapackpp authors
> 
> I have never said that. ;) I took a look at the old lapack++ classes from 96
> and it's almost unbelievable that there are errors inside these functions
> for more than 10 years.

I totally agree.

>> and it turns out this function is already
>> available as Blas_R1_Update(),
> 
> Found it, thanks. :) The bad with these old lapack++ code
> is that these parts you have never touched are not documented and
> if you don't know the correct phrase or Fortran-Name you
> probably will never found it. :(

Yes. When I'm looking for something I'd usually start with the LAPACK
documentation at http://www.netlib.org/lapack/lug/lapack_lug.html , and
if there is a LAPACK routine, then I'd grep over the full lapackpp
source code to see whether it is being used anywhere.

> Maybe I will have documented the two most important files
> sybmd.h and sybfd.h tomorrow.
> 
> Another question concerning the changed. How far can I change it?
> I think the LaSymmBandFactDouble is ... hm, to be honest, useless.
> The functions inside can be used with the simple
> LaSymmBandMatDouble. But however it works.. I think this is the
> important part. ;)

I agree that several of the FactDouble classes are indeed relatively
useless. I have added the class LaGenQRFactComplex
http://lapackpp.sourceforge.net/html/classLaGenQRFactComplex.html and I
consider it useful. It isn't anything more than a wrapper around the
matrix A and vector Tau that make up the complex-valued QR decomposition
in LAPACK, but it additionally encapsulates the two other interesting
functions that would need these A and Tau as input.

In other words, if the existing factorization class is useless, just go
ahead and throw it out and/or replace it by your own class if you came
up with a design that is more useful.

Regards,

Christian
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