Dear Gabriel,
thank you for letting me know.
Good luck with your code!
Bedrich
On Wed, Feb 16, 2011 at 8:27 AM, GG BalintKurti
<Gabriel.BalintKurti@Domain.Removed> wrote:
Dear Bedrich,
Thank you again for your response. I now think that my problems are of my
own making and are not caused by any failure of the dsyev routine.
Again  thank you for your trouble.
Gabriel BalintKurti
On 15 February 2011 09:17 0700 Bedrich Sousedik
<bedrich.sousedik@Domain.Removed> wrote:
Dear Gabriel,
this indeed seems unexpected.
Can you please send me your sample (8x8) matrix and a piece of your code
(small extract that would reproduce the problem you are running into).
Thank you,
Bedrich
On Mon, Feb 14, 2011 at 4:07 PM, GG BalintKurti
<Gabriel.BalintKurti@Domain.Removed> wrote:
Dear LAPACK,
I have been using subroutines dsyev and dsyevd to compute the
eigenvectors and eigenvalues of a symmetric 8x8 matrix. the matrix
formed by these eigenvectors should form a unitary matrix and therefore
be the basis of a unitary transformation. When I test the unitariy of
the resulting matrix I find that it is quite inaccurate. In particular I
find that the scalar product of two of the eigenvectors is 3.8D5. this
is far less accurate than I would like. As I need to perform at least
40,000 unitary transformations in my dynamical calculations such a large
error allows a large buildup of errors and renders my calculations
invalid.
All my variables are double precision. Can you advise as to how I can
improve the accuracy of my eigenvectors.
Gabriel BalintKurti
Professor of Theoretical Chemistry

Gabriel BalintKurti
Centre for Computational Chemistry
School of Chemistry
University of Bristol
Bristol, BS8 1TS
Tel: +44 117 928 7662
fax: +44 117 925 1295
Gabriel.BalintKurti@Domain.Removed
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Gabriel BalintKurti
Centre for Computational Chemistry
School of Chemistry
University of Bristol
Bristol, BS8 1TS
Tel: +44 117 928 7662
fax: +44 117 925 1295
Gabriel.BalintKurti@Domain.Removed
