NAME

       y0, y1, yn - Bessel functions of the second kind

SYNOPSIS

       #include <math.h>

       double y0(double x);
       double y1(double x);
       double yn(int n, double x);

DESCRIPTION

       The y0(), y1(), and yn() functions shall compute Bessel functions of x of the second kind of orders 0, 1,
       and n, respectively.

       An   application   wishing   to   check   for  error  situations  should  set  errno  to  zero  and  call
       feclearexcept(FE_ALL_EXCEPT) before calling  these  functions.   On  return,  if  errno  is  non-zero  or
       fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.

RETURN VALUE

       Upon  successful  completion,  these  functions shall return the relevant Bessel value of x of the second
       kind.

       If x is NaN, NaN shall be returned.

       If the x argument to these functions is negative, -HUGE_VAL or NaN shall be returned, and a domain  error
       may occur.

       If x is 0.0, -HUGE_VAL shall be returned and a range error may occur.

       If the correct result would cause underflow, 0.0 shall be returned and a range error may occur.

       If  the  correct  result  would  cause overflow, -HUGE_VAL or 0.0 shall be returned and a range error may
       occur.

ERRORS

       These functions may fail if:

       Domain Error
              The value of x is negative.

       If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set to [EDOM].
       If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero,  then  the  invalid  floating-
       point exception shall be raised.

       Range Error
              The value of x is 0.0, or the correct result would cause overflow.

       If  the  integer  expression  (math_errhandling  &  MATH_ERRNO)  is  non-zero, then errno shall be set to
       [ERANGE]. If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero,  then  the  overflow
       floating-point exception shall be raised.

       Range Error
              The value of x is too large in magnitude, or the correct result would cause underflow.

       If  the  integer  expression  (math_errhandling  &  MATH_ERRNO)  is  non-zero, then errno shall be set to
       [ERANGE]. If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then  the  underflow
       floating-point exception shall be raised.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       On  error,  the  expressions  (math_errhandling & MATH_ERRNO) and (math_errhandling & MATH_ERREXCEPT) are
       independent of each other, but at least one of them must be non-zero.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       feclearexcept() , fetestexcept() , isnan() , j0() , the Base Definitions volume of  IEEE Std 1003.1-2001,
       Section 4.18, Treatment of Error Conditions for Mathematical Functions, <math.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition,
       Standard  for  Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers,
       Inc and The Open Group. In the event of any discrepancy between this version and the  original  IEEE  and
       The  Open  Group  Standard,  the  original  IEEE and The Open Group Standard is the referee document. The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group                                   2003                                                 Y0(P)