Re: [Help-gsl] gsl_linear_interp example

[Daniel J Farrell]

Hello,

Ended up figuring it out.

Cheers,

Dan.

For future reference:

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <gsl/gsl_interp.h>

int main (void)
{
      //sample data
      double x[4] = { 1970, 1980, 1990, 2000 };
      double y[4] = {   12,   11,   14,   13 };

      //inialise and allocate the gsl objects
      gsl_interp *interpolation = gsl_interp_alloc 
(gsl_interp_linear,n);
      gsl_interp_init(interpolation, x, y, n);
      gsl_interp_accel * accelerator =  gsl_interp_accel_alloc();

      //get interpolation for x = 1981
      double value = gsl_interp_eval(interpolation, x, y, 1981,  
accelerator);

      printf("\n%g",value);

      //output:
      //11.3

  return 0;
}

On 6 Jun 2007, at 14:42, Daniel J Farrell wrote:

> Hello,
>
> I am trying to find example code on how to do a linear  
> interpolation. So far I can allocate and initalise the gsl_interp  
> object, but I get a bit stuck when I need to query it for  
> interpolation values; do I have to use an accelerator?
>
> Any advice?
>
> Regards,
>
> Dan.
>
> ___
>
> #include <stdio.h>
> #include <stdlib.h>
> #include <math.h>
> #include <gsl/gsl_spline.h>
> #include <gsl/gsl_interp.h>
>
> int main (void)
> {
>   unsigned n = 4;
>   double x[n] = { 1970, 1980, 1990, 2000 };
>   double y[n] = {   12,   11,   14,   13 };
>
>   //interpolation
>   gsl_interp *interp = gsl_interp_alloc(gsl_interp_linear,n);
>   gsl_interp_init(interp, x, y, n);
>
>
>   //get interpolation for x = 1981 here...
>
>
>   gsl_interp_free(interp);
>   return 0;
> }
>
>
>
>
>
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