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Numerical (Modern) Fortran. Library for Simple Numerical computing
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qcheb Interface Reference

Subroutine qcheb computes the coefficients of the Chebyshev series expansion of degrees 12 and 24 of a function using a fast Fourier transform method. More...

Detailed Description

Subroutine qcheb computes the coefficients of the Chebyshev series expansion of degrees 12 and 24 of a function using a fast Fourier transform method.

\[ f(x) = \sum_{k} (\mathrm{Cheb}(k) T_{k-1}(x) , \]

where $ T_{k}(x)$ is the Chebyshev polynomial of degree k.

Reference: Robert Piessens, Elise de Doncker-Kapenger, Christian Ueberhuber, David Kahaner, QUADPACK, a Subroutine Package for Automatic Integration, Springer Verlag, 1983. (Section 2.2.3.2)

Parameters
[in]x(real, dimension(11)) values of $ \cos(k*\pi/24)$, for $k = 1, \dots, 11 $
[in,out]fval(real or complex, dimension(25))
[out]cheb12(real or complex) the Chebyshev coefficients for degree 12
[out]cheb24(real or complex) the Chebyshev coefficients for degree 24
The documentation for this interface was generated from the following file: