Hello, Thank for the suggestions.
However, here is the problem. The "singularities" at x=x0 I guess. If I use QAGP and I provide the singular points, then I get: Error during integration: 7168.4707442 (420) integral or series is divergent If I use gsl_integration_cquad there is not error, but I get a wrong value at one of the "singularities" Then I do not see any solution. For the interval, I can calculate the limits. It is not an issue for now. The behavior is the same, what ever is the values are. =========================================================================== Patrick DUPRÉ | | email: pdu...@gmx.com Laboratoire interdisciplinaire Carnot de Bourgogne 9 Avenue Alain Savary, BP 47870, 21078 DIJON Cedex FRANCE Tel: +33 (0)380395988 =========================================================================== > Sent: Thursday, March 05, 2020 at 2:49 PM > From: "Patrick Alken" <al...@colorado.edu> > To: help-gsl@gnu.org > Subject: Re: Integration > > Hello, did you try transforming the integral to have finite limits (i.e. > https://www.youtube.com/watch?v=fkxAlCfZ67E). Once you have it in this > form, I would suggest trying the CQUAD algorithm: > > https://www.gnu.org/software/gsl/doc/html/integration.html#cquad-doubly-adaptive-integration > > Patrick > > On 3/5/20 2:02 AM, Patrick Dupre wrote: > > Hello, > > > > > > Can I collect your suggestions: > > > > I need to make the following integration: > > > > int_a^b g(x) f(x) dx > > > > where a can be 0 of -infinity, and b +infinity > > g(x) is a Gaussian function > > f(x) = sum (1/((x-x0)^2 + g)) / (1 + S* sum (1 / ((x-x0)^2 + g))) > > > > Typically, f(x) is a fraction whose numerator is a sum of Lorentzians > > and the denominator is 1 + the same sum of Lorentzians weighted by a factor. > > > > Thank for your suggestions > > > > =========================================================================== > > Patrick DUPRÉ | | email: pdu...@gmx.com > > Laboratoire interdisciplinaire Carnot de Bourgogne > > 9 Avenue Alain Savary, BP 47870, 21078 DIJON Cedex FRANCE > > Tel: +33 (0)380395988 > > =========================================================================== > > > > > > >
