[neutron-mc] Monochromator_flat

[Lorenzo Ciampolini]

Hi Ulrich,

For me too that's a bug, the first values up to 0 should be negative. I
did not search for the literature, but I know what Gauss quadrature is and
those X values should be the integration abscissae, which should be
definitely symmetrical around zero (an additional argument is used to
later offset the stuff).

However, you might verify that (at least at the present moment) in the
rest of the component code the Gaussian curves are centered at zero so the
bug is effectless.

Best regards,
Lorenzo
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> Today's Topics:
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>    1. Monochromator_flat (Ulrich C. Wildgruber MPI fuer Metallforschung
> Stuttgart)
>
> --__--__--
>
> Message: 1
> Date: Tue, 20 Apr 2004 16:29:21 +0200
> From: "Ulrich C. Wildgruber MPI fuer Metallforschung Stuttgart"
>  <wildgrub at dxray.mpi-stuttgart.mpg.de>
> To: neutron-mc at risoe.dk
> Organization: MPI fuer Metallforschung Stuttgart
> Reply-To: neutron-mc at risoe.dk
>
> Dear colleagues,
>
> just today I looked at the source code of "Monochromator_flat.comp" and
> got stuck at:
>
>   double Gauss_X[] = {-0.987992518020485, 0.937273392400706,
> 0.848206583410427,
>                  0.724417731360170, 0.570972172608539,
> 0.394151347077563, 0.201194093997435, 0,
> 0.201194093997435,
>                  0.394151347077563, 0.570972172608539,
> 0.724417731360170, 0.848206583410427,
> 0.937273392400706, 0.987992518020485};
>
> Could it be that the lonely minus-sign attached to the first element is
> wrong or that other minus signs are missing? I wasn't able to get hold
> of the literature mentioned in the source listing.
> (/* Values for Gauss quadrature. Taken from Brice Carnahan, H. A. Luther
> and
>       James O Wilkes, "Applied numerical methods", Wiley, 1996, page
> 103. */)
>
> Can anybody please confirm that everything is all right?
>
> Thanks!
>
> Uli
>
> --
> Ulrich WILDGRUBER
> wildgrub at dxray.mpi-stuttgart.mpg.de
> wwwmf.mpi-stuttgart.mpg.de/abteilungen/dosch/dosch.html
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**********************************
Lorenzo Ciampolini, Dr. Sc. Techn.
Ingénieur Calcul et Développement
Università di Parma
Tel: +33 4 76 20 70 71
c/o Institut Laue-Langevin
6, rue Jules Horowitz BP 156
F-38042 Grenoble cedex 9
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