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Bessel function of second kind of integer order.


double x, y, yn();
int n;
y = yn(n, x);


Returns a Bessel function of order n, where n is a (possibly negative) integer.
The function is evaluated by forward recurrence on n, starting with values computed by the routines y0() and y1().
If n = 0 or 1 the routine for y0 or y1 is called directly.

                      Absolute error, except relative
                      when y > 1:
arithmetic   domain     # trials      peak         rms
    DEC       0, 30        2200       2.9e-16     5.3e-17
    IEEE      0, 30       30000       3.4e-15     4.3e-16


message         condition      value returned
singularity       x = 0           MAXNUM
overflow                          MAXNUM

Spot checked against tables for x, n between 0 and 100.