Re: [Help-gsl] monotone interpolation

[Christian Krueger]

True. I wonder why there is nothing like that implemented in GSL.

In case I understand the code, I could maybe do it. In principle, the 
method is not complicated, but the code looks like it needs some time to 
understand it...


On 03/02/2012 05:06 AM, Andrew W. Steiner wrote:
> Hello all,
>
>       Just in case it hasn't been said explicitly, a GSL interpolation type 
> which
> preserves monotonicity and keeps the same interface as the other GSL
> interpolation types would certainly be welcome!
>
> Take care,
> Andrew
> http://o2scl.sourceforge.net
>
> On Fri, Mar 2, 2012 at 10:57 AM, Feng Chen<address@hidden>  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>
> > 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