Digital

NAME

bessel, j0, j1, jn, y0, y1, yn − Computes Bessel functions. 

LIBRARY

Math Library (libm.a)

SYNOPSIS

#include <math.h>

double j0 (
  double x);
double y0 (
  double x);
double j1 (
  double x);
double y1 (
  double x);
double jn (
  int n,
  double x);
double yn (
  int n,
  double x);

PARAMETERS

xSpecifies a double value.  The value of x must be positive for the y0(), y1(), and yn() functions. 

nSpecifies some integer value. 

DESCRIPTION

The j0(), j1(), jn(), y0(), y1(), and yn() functions are Bessel functions that are used to compute wave variables, primarily in the field of communications. 

NOTES

AES Support Level:
Trial use

RETURN VALUES

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

If the x argument is too large in magnitude, the value 0 (zero) is returned.  If x is NaN (Not a Number), NaN is returned.  Otherwise, either errno is set to indicate the error or NaN is returned. 

The y0() and y1() functions return the Bessel functions of x of the second kind, of orders 0 (zero) and 1, respectively. The yn() function returns the Bessel function of x of the second kind of order n. 

If the x argument to the functions y0(), y1() or yn() is nonpositive, NaN is returned.  Otherwise, NaN is returned and also errno is set to indicate the error. 

ERRORS

If the j0(), j1(), or jn() function fails, errno may be set to one of the following values:

[EDOM]The value of x is NaN. 

[ERANGE]The value of x was too large in magnitude. 

If the y0(), y1() or yn() function fails, errno may be set to one of the following values:

[EDOM]The value of x is nonpositive or NaN. 

[ERANGE]The value of x was too large in magnitude. 

ENVIRONMENT

In the SVID-2 habitat:

Non-positive arguments cause y0(), y1(), and yn(), to return the value −HUGE and to set errno to EDOM.  In addition, a message that indicates DOMAIN error is printed on the standard error output. 

Arguments too large in magnitude cause j0(), j1(), y0(), and y1() to return zero and to set errno to ERANGE. In addition, a message that indicates TLOSS is printed on the standard error output. 

Error-handling procedures can be changed with the matherr() function. 

RELATED INFORMATION

Functions: math(3), matherr(3)