ultrix man page for y1

bessel(3m)																bessel(3m)

Name
       j0, j1, jn, y0, y1, yn - bessel functions

Syntax
       #include <math.h>

       double j0(x)
       double x;

       double j1(x)
       double x;

       double jn(n,x)
       double x;

       double y0(x)
       double x;

       double y1(x)
       double x;

       double yn(n,x)
       double x;

Description
       These functions calculate bessel functions of the first and second kinds for real arguments and integer orders.

Return Values
       Negative arguments cause and to return NaN.  Arguments too large in magnitude cause and to return NaN.

       Arguments too large in magnitude cause and to return zero.

Environment
       When  your program is compiled using the System V environment, nonpositive arguments cause and to return the value HUGE and to set errno to
       EDOM.  In addition, a message indicating DOMAIN error is printed on the standard error output.

       Arguments too large in magnitude cause and to return zero and to set errno to ERANGE.  In addition, a message  indicating  TLOSS  error	is
       printed on the standard error output.

       These error-handling procedures may be changed with the function.

See Also
       math(3m)

								       RISC								bessel(3m)