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## Re: [Help-gsl] QAWF integration algorithms and low frequencies

**From**: |
Simone Pigolotti |

**Subject**: |
Re: [Help-gsl] QAWF integration algorithms and low frequencies |

**Date**: |
Fri, 19 Sep 2008 13:08:11 +0200 |

these is the error message:
>* gsl: qag.c:261: ERROR: could not integrate function*
>* Default GSL error handler invoked.*
I manage to solve the problem using QAWO (not QAWF) in a FINITE
interval, truncating the gaussian after, say, 10 standard deviation. But
apparently
the algorithms treating oscillating integrals in an INFINITE interval have
problems for
small frequencies when the integrand decays very quickly (like Gaussian).
Simone
2008/9/18 Brian Gough <address@hidden>
>* At Wed, 17 Sep 2008 19:42:25 +0200,*
>* Simone Pigolotti wrote:*
>* > so it means that the algorithm is not supposed to work for small*
>* > omega's. I don't know if this can be considered a bug since I'm*
>* > using the algorithm in a parameter range where it is not supposed to*
>* > work. Certainly, it is a problem since for small omega I don't know*
>* > how to perform the integral (QAGI integration refuses to handle*
>* > oscillating integrals even for small frequencies).*
>
>* In what way does it refuse? e.g. what is the error code returned?*
>
>* --*
>* Brian Gough*
>
>* GNU Scientific Library -*
>* http://www.gnu.org/software/gsl/*
>