[pygsl-discuss] Chebyshev approximation to grid points

[<jo...@jo...>]

Hi All,

we'd like to use GSL (or pygsl, for that matter) to get Chebyshev
approximations (polynomial degrees on the order of approx. ten) to
tabulated values (currently all equidistant). I cannot find a free
implementation, maybe someone can help out? Does anybody have a
function to do it? Otherwise I would need to write one myself.

There is a function in NAG to perform this, they give the following
references; can anybody help me getting them, esp. ref. 2 and 3?
,----
| Clenshaw C W (1960) Curve fitting with a digital computer Comput. J. 2
| 170-173
|=20
| Cox M G (1974) A data-fitting package for the non-specialist user
| Software for Numerical Mathematics (ed D J Evans) Academic Press
|=20
| Cox M G and Hayes J G (1973) Curve fitting: a guide and suite of
| algorithms for the non-specialist user NPL Report NAC26 National
| Physical Laboratory
|=20
| Forsythe G E (1957) Generation and use of orthogonal polynomials for
| data fitting with a digital computer J. Soc. Indust. Appl. Math. 5
| 74-88
|=20
| Gentleman W M (1969) An error analysis of Goertzel's (Watt's)
| method for computing Fourier coefficients Comput. J. 12 160-165
|=20
| Hayes J G (ed.) (1970) Curve fitting by polynomials in one variable
| Numerical Approximation to Functions and Data Athlone Press, London
`----

Do you know other/better (or easier to get) literature?

Thank you in advance.

Greetings,
Jochen
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