k1Modified Bessel function, third kind, order one.
double x, y, k1();
y = k1(x);
Computes the modified Bessel function of the third kind, of order one of the argument.
The range is partitioned into the two intervals [0,2] and (2, infinity). Chebyshev polynomial expansions are employed in each interval.
arithmetic domain # trials peak rms
DEC 0, 30 3300 8.9e-17 2.2e-17
IEEE 0, 30 30000 1.2e-15 1.6e-16
message condition value returned
domain x <= 0 MAXNUM