bessel(3M)                     DG/UX R4.11MU05                    bessel(3M)


NAME
       bessel: j0, j1, jn, y0, y1, yn - Bessel functions

SYNOPSIS
       cc [flag ...] file ...  -lm [library ...]

       #include <math.h>

       double j0 (double x);

       double j1 (double x);

       double jn (int n, double x);

       double y0 (double x);

       double y1 (double x);

       double yn (int n, double x);

DESCRIPTION
       j0 and j1 return Bessel functions of x of the first kind of orders 0
       and 1, respectively.  jn returns the Bessel function of x of the
       first kind of order n.

       y0 and y1 return Bessel functions of x of the second kind of orders 0
       and 1, respectively.  yn returns the Bessel function of x of the
       second kind of order n.  The value of x must be positive.

   Considerations for Threads Programming
                     +---------+-----------------------------+
                     |         |                      async- |
                     |function | reentrant   cancel   cancel |
                     |         |             point     safe  |
                     +---------+-----------------------------+
                     |j0       |     Y         N        N    |
                     |j1       |     Y         N        N    |
                     |jn       |     Y         N        N    |
                     |y0       |     Y         N        N    |
                     |y1       |     Y         N        N    |
                     |yn       |     Y         N        N    |
                     +---------+-----------------------------+
DIAGNOSTICS
       When the -Xt compilation option is used, negative arguments cause y0,
       y1, and yn to return -HUGE and to set errno to EDOM.  In addition, a
       message indicating DOMAIN error is printed on the standard error
       output.

       When the -Xa or -Xc compilation options are used, negative arguments
       cause y0, y1, and yn to return IEEE NaN and set errno to EDOM.

       Arguments too large in magnitude cause j0, j1, jn, y0, y1, and yn to
       return 0 and to set errno to ERANGE.  In addition, a message
       indicating TLOSS error is printed on the standard error output.

       An argument of zero causes y0, y1, and yn to return -HUGE and set
       errno to EDOM.  In addition, a message indicating DOMAIN error is
       printed on the standard error output.

       For each of these functions, if x is a quiet NaN, that value is
       returned.  If x is a signaling NaN, a quiet NaN is returned and an
       invalid operation exception is raised.  In either case, errno is set
       to EDOM, and a message indicating DOMAIN error is printed on the
       standard error output.

       When the -Xt compilation option is used, these error-handling
       procedures may be changed with the function matherr.  When the -Xa or
       -Xc compilation options are used, HUGEVAL is returned instead of
       HUGE and no error messages are printed.

SEE ALSO
       cc(1), reentrant(3), matherr(3M), fpsetmask(3C).


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