Re: interp2d discussion

[Patrick Alken <patrick dot alken at Colorado dot EDU>]

> Sure, that would be a reasonable option, but I'd like to do a bit of
> research (i.e. ask a few more people for opinions) to see what solution
> will be the least confusing. After all, if there is a change to be made,
> this is the time to do it, not later after the code is incorporated into
> GSL. I think backward compatibility will not be too much of a problem
> because people will have to make other changes anyway to transition from
> the interp2d_* functions to the corresponding gsl_* functions.

I think 2 additional functions could be added to help solve this issue 
and hide the indexing
from the user:

interp2d_grid_set(double zarr[], size_t i, size_t j, double z)
{
  /* set point (i,j) of grid 'zarr' to value 'z' */
}

and

interp2d_grid_fill(double zarr[], int (*grid_func)(double x, double y, 
void *params))
{
  /* fill entire grid 'zarr' using callback function 'grid_func'; this 
would be useful
   * in cases where the user has a continuous/analytic function which 
is expensive to call, but
   * they'd like to make a grid and then interpolate from it
   */
}