SAS/C Library Reference, Vol. 1

j1 -- Bessel Function of the First Kind, Order 1

SYNOPSIS

 #include <lcmath.h>

 double j1(double x);

DESCRIPTION

j1 computes the Bessel function of the first kind with order 1 of the value x.

RETURN VALUE

j1 returns the Bessel function of the first kind with order 1 of the argument x, provided that this value is computable.

DIAGNOSTICS

If the magnitude of x is too large (|x| >= 6.7465e9), j1 returns 0.0. In this case, the message "total loss of significance" is also written to stderr (the standard error file).

If an error occurs in j1, the _matherr routine is called. You 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 first kind, of order 1
at x = 5 using j1:

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

  main()
  {
     double y;
     y = j1(5.);
     printf("j1(5.) = %lfn", y);
  }

RELATED FUNCTIONS

j0, jn, _matherr, y0, y1, yn