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Re: gsl_function

 From: Patrick Dupre Subject: Re: gsl_function Date: Tue, 16 Jun 2020 11:58:06 +0200

```Thanks for the feedback.

Humm,
Can I void to make the same calculation twice?
One time to integrate the real part, and one time to integrate the imaginary
part?

Thanks.

===========================================================================
Patrick DUPRÉ                                 | | email: pdupre@gmx.com
Laboratoire interdisciplinaire Carnot de Bourgogne
9 Avenue Alain Savary, BP 47870, 21078 DIJON Cedex FRANCE
Tel: +33 (0)380395988
===========================================================================

> Sent: Tuesday, June 16, 2020 at 10:45 AM
> To: "Patrick Dupre" <pdupre@gmx.com>
> Cc: help-gsl@gnu.org
> Subject: Re: gsl_function
>
> Hi Patrick,
>
> you can't return a complex with gsl_function.
>
> Integrate the real and imaginary parts separately.
>
> Best regards,
>
>
>
> Patrick Dupre kirjoitti 16.6.2020 klo 11.29:
> > Hello,
> >
> > I need to return a complex with a gsl_function.
> > How can I do?
> >
> > Here is an example
> >
> > #include <math.h>
> > #include <stdio.h>
> > #include <complex.h>
> > #include <gsl/gsl_integration.h>
> >
> > double complex tt (double complex z) {
> >   double complex y = 0 ;
> >   for (unsigned short int i = 0 ; i < 5 ; i++) {
> >     y += z ;
> >     }
> >   return y ;
> >   }
> >
> > main () {
> >   gsl_function fcn ;
> >   double complex y0 = 1 + I * 0.5 ;
> >   fcn.function = &tt ;
> >   double complex z = tt (y0) ;
> >   double complex zz = (double complex) fcn.function (y0, fcn.params) ;
> >   printf ("%g %g, %g %g\n", z, zz) ;
> >   }
> >
> > Result (zz is not correct)
> > 5 2.5, 5 0
> >
> > Some ideas?
> >
> > Thanks
> >
> > ===========================================================================
> >  Patrick DUPRÉ                                 | | email: pdupre@gmx.com
> >  Laboratoire interdisciplinaire Carnot de Bourgogne
> >  9 Avenue Alain Savary, BP 47870, 21078 DIJON Cedex FRANCE
> >  Tel: +33 (0)380395988
> > ===========================================================================
> >
> >
>

```