[Help-gsl] monotone interpolation

[Christian Krueger]

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