[Gambas-user] Gambas3 and Gnu scientific library

[Jussi Lahtinen]

Benoit keeps on amazing us!

Jussi
P.S. I haven't test it yet...



On Wed, May 18, 2011 at 18:21, wally <wally at ...2037...> wrote:

>
> Thanks a lot ! :)
> wally
>
> On Wednesday, May 18, 2011 17:07:09 Benoît Minisini wrote:
> > > Hello  Jussi,
> > >
> > > in C the stuff works pretty nice, so i agree to your suggestion 2.
> > >
> > > Do all math stuff directly in Gambas is an option i should check.
> > >
> > > I think i mentioned that i use Gambas3 and want to make interpolations,
> > > derivatives and integrals from an integrarray.
> > > The array contains ADC outputs from a CCD linear array sensor
> measurment
> > >
> > > wally
> > >
> > > On Monday, May 16, 2011 17:46:51 Jussi Lahtinen wrote:
> > > > Not very easy task...
> > > > Here is interpolation example in C.
> > > >
> http://www.gnu.org/software/gsl/manual/html_node/Interpolation-Example-
> > > > pr og rams.html
> > > >
> > > > As you can see, you need to call several functions to get what you
> > > > want. Declaring those in Gambas is OK, except determining
> > > > interpolation type!
> > > >
> > > > You can find definition of interpolation type from "gsl_interp.h",
> > > > and unfortunately it is not anything simple;
> > > >
> > > > typedef struct {
> > > >
> > > >   const char * name;
> > > >   unsigned int min_size;
> > > >   void *  (*alloc) (size_t size);
> > > >   int     (*init)    (void *, const double xa[], const double ya[],
> > > >   size_t
> > > >
> > > > size);
> > > >
> > > >   int     (*eval)    (const void *, const double xa[], const double
> > > >   ya[],
> > > >
> > > > size_t size, double x, gsl_interp_accel *, double * y);
> > > >
> > > >   int     (*eval_deriv)  (const void *, const double xa[], const
> double
> > > >
> > > > ya[], size_t size, double x, gsl_interp_accel *, double * y_p);
> > > >
> > > >   int     (*eval_deriv2) (const void *, const double xa[], const
> double
> > > >
> > > > ya[], size_t size, double x, gsl_interp_accel *, double * y_pp);
> > > >
> > > >   int     (*eval_integ)  (const void *, const double xa[], const
> double
> > > >
> > > > ya[], size_t size, gsl_interp_accel *, double a, double b, double *
> > > > result); void    (*free)         (void *);
> > > >
> > > > } gsl_interp_type;
> > > >
> > > > GSL_VAR const gsl_interp_type * gsl_interp_cspline; * <-- this is
> used
> > > > in example*
> > > >
> > > >
> > > > Right now I don't know how to implement that reasonably in Gambas.
> > > > There are at least three possibilities to overcome this problem:
> > > >
> > > > 1. Hope that Benoit will implement new feature to use external
> > > > structures. 2. Use C to write your own interface between GSL and
> > > > Gambas. Perhaps easiest option.
> > > > 3. Do not use GSL at all, and write what you need purely with Gambas.
> > > >
> > > > That's all I can say...
> > > > Also because you didn't specify what you need exactly, nor are you
> > > > using Gambas 2 or 3.
> > > >
> > > > Jussi
> >
> > Hi,
> >
> > I added a System.GetExternSymbol() method in the last revision so that
> you
> > can get the address of the interpolation type structure.
> >
> > You have to do something like that:
> >
> >       Dim gsl_interp_cspline As Pointer
> >
> >       gsl_interp_cspline = Pointer@(System.GetExternSymbol("libgsl",
> >               "gsl_interp_cspline"))
> >
> > Maybe the Pointer@() is not needed, I don't know. The symbol can be
> > directly the address of the structure (no Pointer@ needed), or a pointer
> > to the address of the structure.
> >
> > Try and tell me.
> >
> > Regards,
>
>
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