XLPack 7.0
XLPack Numerical Library (C API) Reference Manual
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◆ cbesk()

void cbesk ( doublecomplex  z,
double  nu,
int  kode,
int  n,
doublecomplex  y[],
int *  info 
)

Sequence of the modified Bessel functions of the second kind Kν(z) (fractional order) (complex argument)

Purpose
cbesk computes the sequence of the modified Bessel functions of the second kind Kν(z) for complex nonzero argument z and real nonnegative orders ν, ν+1, ...
A scaling option is available to help avoid overflow.
Parameters
[in]zArgument z. (z != 0)
[in]nuOrder of first member of the sequence. (nu >= 0)
[in]kodeA parameter to indicate the scaling option.
= 1: No scaling.
= 2: Returns exponentially scaled values.
[in]nNumber of members in the sequence. (n members of orders nu to nu+n-1 to be computed) (n >= 1)
[out]y[]Array y[ly] (ly >= n)
Sequence of Bessel functions of the second kind.
kode = 1: Kν(z) (ν = nu to nu+n-1)
kode = 2: exp(z)*Kν(z) (ν = nu to nu+n-1)
[out]info= 0: Successful exit.
= -1: The argument z had an illegal value. (z = 0)
= -2: The argument nu had an illegal value. (nu < 0)
= -3: The argument kode had an illegal value. (kode != 1 and kode != 2)
= -4: The argument n had an illegal value. (n < 1)
= nz (0 < nz <= n): The last nz components of y[] set to zero due to underflow.
= n+1: Precision warning. (Half precision or less because abs(z) or nu+n-1 is large)
= n+2: Precision error. (No precision because abs(z) or nu+n-1 is too large)
= n+3: Overflow abs(z) too small and/or nu+n-1 too large.
= n+4: Algorithmic error. (Termination condition not met)
Reference
SLATEC