XLPack 7.0
XLPack Numerical Library (Excel VBA) Reference Manual
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◆ Chebu()

Function Chebu ( N As  Long,
X As  Double,
Optional Info As  Long 
)

Chebyshev polynomial of second kind Un(x)

Purpose
Computes the Chebyshev polynomial of the second kind Un(x).
Un-1(x) = sin(nt)/sin(t), where x = cos(t)
This polynomial follows the recurrence formula:
Un+1(x) = 2xUn(x) - Un-1(x), where U0(x) = 1, U1(x) = 2x (n > 0)
Returns
Double
Chebyshev polynomial of second kind Un(x).
Parameters
[in]NArgument n. (N > 0)
[in]XArgument x.
[out]Info(Optional)
= 0: Successful exit.
= -1: The argument N had an illegal value. (N <= 0)
= 1: Floating point range error.
Reference
boost/math/special_functions