Re: [Help-gsl] monotone interpolation

[Christian Krueger]

Interesting. Other possibilities are of course welcome.

The other one in that graph *might* be close to the one on wiki? 
http://en.wikipedia.org/wiki/Monotone_cubic_interpolation
I will read that paper soon.

However, I would prefer to have a GSL implementation.

I implemented the wikipedia suggestion already quick&dirty, but I am not 
entirely happy with that. It is sometimes more wiggly than a usual CSpline.


On 03/02/2012 01:57 AM, Feng Chen wrote:
> How about this one? (The green curve does not look like monotonic to me
> though ... The blue curve is the reference you cited)
> MESA/INTERP_1D
> monotonicity preserving cubic interpolation
> piecewise monotonic cubic interpolation
> http://mesa.sourceforge.net/interp_1D.html
> On Thu, Mar 1, 2012 at 1:30 PM, Christian Krueger <address@hidden
> <mailto:address@hidden>> wrote:
>  >
>  > Hi... is there any possibility to get a strictly monotone
> interpolation function?
>  >
>  > I have data which for sure have to be monotone, but the provided
> interpolation methods (cspline, akima) do not preserve this condition
> (linear interpolation is not smooth and polynomial of course useless
> with 200+ datapoints).
>  >
>  > I wonder whether the method of Steffen (1990) is implemented
> somewhere which seem to have some nice features (monotonicity, almost no
> spurious oscillations)? Or might it be a useful extension for GSL?
>  > Found in this paper: A simple method for monotonic interpolation in
> one dimension, Astron. Astrophys. 239, 443 (1990)
>  >
>  >
>  > Regards,
>  > Christian
>  >