j0Bessel function of order zero.
double x, y, j0();
y = j0(x);
Returns a Bessel function of order zero of the argument. The domain is divided into the intervals [0, 5] and (5, infinity). In the first interval this rational approximation is used:
(w - r ) (w - r ) P (w) / Q (w)
1 2 3 8
where w = x and each r is a zero of the function.
In the second interval, the Hankel asymptotic expansion is employed with two rational functions of degree 6/6 and 7/7.
arithmetic domain # trials peak rms
DEC 0, 30 10000 4.4e-17 6.3e-18
IEEE 0, 30 60000 4.2e-16 1.1e-16