SAS/C Library Reference, Vol. 1

y1 -- Bessel Function of the Second Kind, Order 1

SYNOPSIS

 #include <lcmath.h>

 double y1(double x);

DESCRIPTION

y1 computes the order 1 Bessel function of the second kind of the value x.

RETURN VALUE

y1 returns the order 1 Bessel function of the second kind of the argument x, provided that this value is computable.

DIAGNOSTICS

If the value of x is 0.0, a diagnostic message is written to the standard error file (stderr) and the function returns -HUGE_VAL, the largest negative floating-point number that can be represented.

If the magnitude of x is too large (|x| >= 6.7465e9), y1 returns 0.0. In this case, the message "total loss of significance" is written to stderr.

If the magnitude of x is too close to 0 (|x| < approximately 8.032e-77), an overflow error occurs during computation of y1. In this case, a diagnostic message is written to stderr, and y1 returns -HUGE_VAL.

If an error occurs in y1, the _matherr routine is called. You can supply your own version of _matherr to suppress the diagnostic message or modify the value returned.

EXAMPLE

This example computes the Bessel function of the second kind, of order 1 at
x = 5:

  #include <stdio.h>
  #include <lcmath.h>

  main()
  {
     double y;
     y = y1(5.);
     printf("y1(5.) = %lfn", y);
  }

RELATED FUNCTIONS

j0, j1, jn, _matherr, y0, yn