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Chebyshev polynomials

The Chebyshev polynomials of the first (T and second (U) kinds can be defined by the trigonometric identity

T(x) = cos(n arccos x)
U(x) = sin((n+1) arccos x) / sin( arccos x)

or can be constructed using the three term recurrence relation:

T(x) = 1
T(x) = x
Tn+1 (x) = 2xT(x) - Tn-1 (x)
U(x) = 1
U(x) = 2x
Un+1 (x) = 2xT(x) - Tn-1 (x)

Unit description

The recurrence relation given above is the most efficient way to calculate the Chebyshev polynomial. The ChebyshevCalculate subroutine uses this relation to calculate T(x) and/or U(x) for any given x.

The ChebyshevSum subroutine calculates the sum of Chebyshev polynomials cT(x) + cT(x) + ... + cT(x) using Clenshaw's recurrence formula.

The ChebyshevCoefficients subroutine can represent T(x) as a sum of powers of x: c + cx + ... + cx n.

The FromChebyshev subroutine can perform a conversion of a series of Chebyshev polynomials to a power series.

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Source codes

C#

C# 1.0 source.
chebyshev.csharp.zip - Chebyshev polynomials


C++

C++ source.
chebyshev.cpp.zip - Chebyshev polynomials
ablas.zip - optimized basic linear algebra subroutines with SSE2 support (for C++ sources only)


Delphi

Delphi source.
Can be compiled under FPC (in Delphi compatibility mode).
chebyshev.delphi.zip - Chebyshev polynomials


Visual Basic 6

Visual Basic 6 source.
chebyshev.vb6.zip - Chebyshev polynomials


Zonnon beta

Zonnon source.
Zonnon is an experimental language developed at ETH Zurich.
See www.zonnon.ethz.ch for more information.
chebyshev.zonnon.zip - Chebyshev polynomials



 
 
Sergey Bochkanov, Vladimir Bystritsky
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