Boost logo

Ublas :

Subject: Re: [ublas] Eigenvalues & -vectors
From: Kraus Philipp (philipp.kraus_at_[hidden])
Date: 2010-07-05 18:23:21

Am 05.07.2010 um 23:43 schrieb Thomas Klimpel:

> Kraus Philipp wrote:
>> I think there was a little mistake, because "lower" means, that the
>> values must be filled into the upper triangle.
> You're joking, right? The MKL example used "Upper" to compensate for
> the differences between C's row_major and fortran's column_major
> matrix storage format.
> For your example, the matrix
> 1 0 0
> 2 2 0
> 3 3 4
> will certainly give the eigenvalues (4,2,1) with Matlab. When you're
> calling syev with this matrix as "upper", syev will interpret it as
> the symmetric matrix

I'm not joking. For the symmetric matrix it return the correct values
(also in my C++ and Matlab code), but in my first posting I have
maked a mistake. I don't need a symmetric matrix, but only a square
and not-symmetric matrix. The whole code that I had written, was/is
wrong, because my input matrix is not symmetric, so I can't use, syev,
I must use geev. That was a misunderstanding, because I came from a
different context