Please note : This help page is not for the latest version of Enterprise Architect. The latest help can be found here.

Prev Next

y1

Bessel function of second kind of order one.

SYNOPSIS:

double x, y, y1();
y = y1(x);

DESCRIPTION:

Returns a Bessel function of the second kind of order one of the argument.

The domain is divided into the intervals [0, 8] and (8, infinity). In the first interval a 25 term Chebyshev expansion is used, and a call to j1() is required. In the second, the asymptotic trigonometric representation is employed using two rational functions of degree 5/5.


ACCURACY:
                      Absolute error:
arithmetic   domain      # trials      peak         rms
    DEC       0, 30       10000       8.6e-17     1.3e-17
    IEEE      0, 30       30000       1.0e-15     1.3e-16

(error criterion relative when |y1| > 1).