Re: [Lapackpp-devel] tridiagonal

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

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Hi Do Bi,

Christian Stimming schrieb:
> Please can anyone hint me how to correctly form a tridiagonal?
>    I wrote this and tried to print the value, but it was wrong.

indeed you have found a bug in the library. Thanks for providing the
testing code -- this way I could fix this in the library. Basically you
need to write

  Mat.diag(0).inject(Diag);

instead of Mat.diag(0)=Diag; but apart from this there have been various
bugs in the code of the LaTridiagMatDouble class.

These have been fixed in CVS now. Are you familiar with retrieving the
source code from CVS, see http://sourceforge.net/cvs/?group_id=99696 ?
If not, then please tell us so, and then I'll provide an updated
lapackpp-2.4.12 version as soon as possible.

As a hint for you: The header file with the LaTridiagMatDouble class,
include/trmd.h, contained almost no documentation at all. This always
means that the code has never been reviewed by me since its original
lapack++-1.0 version, and it is very likely that it contains bugs and/or
is incomplete. Not that I wouldn't introduce bugs myself, but when I
document and review other code then it has at least been checked by more
than one person. So: The class LaTridiagMatDouble contained various
errors, and the missing documentation were a strong hint that this is
possible. Apart from this I actually don't quite understand what you
want to do with the LaTridiagMat. There aren't any useful functions
available for these, except for LaTridiagMatFactorize in trfd.h ...

Regards

Christian Stimming

>   LaVectorDouble x(M), b(M), const Diag(M), DiagL(M-1), DiagU(M-1);
>   for (int i=0; i< M; i++)
>   Diag(i)=1+2*alfa*0;
>   for (int i=0; i< M-1; i++)
>   DiagL(i)=-alfa;
>   for (int i=0; i< M-1; i++)
>   DiagU(i)=-alfa;
> 
> 
>   for (int i=0; i< M-1; i++)
>   cout << DiagL(i) << endl;
>   LaTridiagMatDouble Mat(M);
>   Mat.diag(0)=Diag;
>   Mat.diag(-1)=DiagL;
>   Mat.diag(1)=DiagU;
>   //for (int i=0; i< M-1; i++)
>   //cout << Diag(i) << endl;
>   cout << Mat(0,0) << endl;
> 
> 
> ---------------------------------
> Yahoo! Music Unlimited - Access over 1 million songs.Try it free.
> 
> -------------------------------------------------------
> 
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.2.1 (MingW32)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

iQCVAwUBRM9TaGXAi+BfhivFAQIZxgP/WDrfUSZvbi28cSxvlMuD9HdFnHnuM8H+
GweXLM6g4jCblLZZK4hUuEsvvhr9C9LROojqjnZhSpGtjxnbVRbdUruotj228FpE
AK5Usws81NMAFpeWdTKBzLrM39Ript99i2tuiEADSLO8L/luq0zshb1DX2I6yxLi
ae8OfNRKdt0=
=bWY1
-----END PGP SIGNATURE-----