approximating a curve



On Tue, 9 Dec 2008 08:21:31 -0700
Robert Dodier wrote:

> On 12/8/08, Valery Pipin  wrote:
> 
> > real life example. Using the Peter's Eggleton stellar evolution code
> >  I've got a table of  the stellar interior parameters for the Brown
> >  Dwarf (0.2 M_sun, 0.006 L_sun). The parameters are pressure,
> >  temperature, luminosity, density and etc.. . Now I want to use
> > their functional form in my dynamo model. The best way is to get the
> >  Chebyshev approximations to them. I do as follows,
> >  1) read the table to maxima
> >  2) find the spline interpolation
> >  3) find  the Chebyshev approximations
> 
> Hey, that rocks. But I don't quite understand what's going on here.
> Why is there both a cubic spline and a Chebyshev approximation?
Agree, it is not an ideal way.
The problem is that I can not use the given spline approximations to
differentiate them further. I have use it to interpolate the table to
the Chebyshev nodes. It was a fast solution (in sense, that everything
is at hands). 

best regards
Valery