j1(x) = <ufunc 'j1'>¶
Bessel function of the first kind of order 1.
Value of the Bessel function of the first kind of order 1 at x.
The domain is divided into the intervals [0, 8] and (8, infinity). In the first interval a 24 term Chebyshev expansion is used. In the second, the asymptotic trigonometric representation is employed using two rational functions of degree 5/5.