Open System Services Library Calls Reference Manual (G06.29+, H06.08+, J06.03+)

OSS Library Calls (w - z) y0(3)
NAME
y0 - Computes the Bessel function of the second kind, of order 0 (zero)
LIBRARY
G-series native Guardian processes: $SYSTEM.SYSnn.ZCRESRL
G-series native OSS processes: /G/system/sysnn/zcresrl
H-series and J-series native Guardian processes: $SYSTEM.ZDLLnnn.ZCREDLL
32-bit H-series and J-series OSS processes: /G/system/zdllnnn/zcredll
64-bit H-series and J-series OSS processes: /G/system/zdllnnn/ycredll
SYNOPSIS
#include <math.h>
double y0(
double x);
PARAMETERS
x Specifies the double value for which the function is to be computed. The value
of x must be positive.
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. The y0( ) function computes the Bessel
function of x of the second kind, of order 0 (zero).
NOTES
This function supports both IEEE Std 754-1985 floating-point and Tandem floating-point values
in the native environment. IEEE values can include NaN and infinity, and the sign of 0.0 (zero)
can be either positive or negative. Refer to the fp_class(3) reference page for a description of
IEEE value classes.
Guardian functions are available to convert between floating-point formats. Refer to the Guar-
dian Programmer’s Guide for a discussion of floating-point conversions.
RETURN VALUES
The y0( ) function returns the Bessel function of x of the second kind, of order 0 (zero).
If the correct result would cause overflow, 0.0 (zero) is returned and errno is set to [ERANGE].
If x is less than or equal to 0.0 (zero), -HUGE_VAL is returned and errno is set to [EDOM].
For IEEE floating-point data, if the value of x is NaN, NaN is returned. If the value of x is posi-
tive infinity, 0.0 is returned and errno is set to [ERANGE].
ERRORS
If any of the following conditions occurs, the y0( ) function sets errno to the corresponding
value:
[EDOM] The value of x is negative.
[ERANGE] The value of x was infinite, or the result would cause overflow.
RELATED INFORMATION
Functions: fp_class(3), isnan(3), j0(3), j1(3), jn(3), y1(3), yn(3).
STANDARDS CONFORMANCE
The XPG4 Version 2 specification leaves some features to the implementing vendor to define.
The following features are affected in the HP implementation:
• For IEEE floating-point data, errno is not set to [EDOM] when the value of x is NaN.
527187-017 Hewlett-Packard Company 8−87