Re: [Help-gsl] getting cubicsline interpolation coefficients

[Rhys Ulerich]

> I'm needing to obtain the cubic spline interpolation co-efficients at each
> abscissa. Is there a way to do this with gsl?

I can't speak for the interpolation routines.

The functionality is not there for the basis splines.  It could be
added, and would look exactly like PPPACK's bsplpp.f (see
http://www.netlib.org/pppack/).  A large portion of the basis spline
code looks like PPPACK under the covers.

> Ideally I would like an array containing an array of coefficients at each
> point. I then need to plug these into a matrix solver as part of a
> collocation solver.

Will forming a mass matrix M_{i,j} by evaluating the j-th basis
function at the collocation points x_i cover what you need?  Sometimes
collocation problems fall into this camp.  If so, the existing
evaluation routines would do what you want.

- Rhys