Guardian Native C Library Calls Reference Manual (G06.28+, H06.05+)

Guardian Native C Library Calls (a - e) cos(3)
NAME
cos - Computes the trigonometric cosine function
LIBRARY
G-series native Guardian processes: $SYSTEM.SYSnn.ZCRESRL
G-series native OSS processes: /G/system/sysnn/zcresrl
H-series native Guardian processes: $SYSTEM.ZDLLnnn.ZCREDLL
H-series OSS processes: /G/system/zdllnnn/zcredll
SYNOPSIS
#include <math.h>
double cos(
double x);
PARAMETERS
x Is the value for which the trigonometric cosine function is to be computed.
DESCRIPTION
The cos() function computes the cosine of x, measured in radians.
NOTES
The cos() function loses accuracy when passed a large value for the x parameter.
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 cos() function returns the cosine of its parameter.
For IEEE floating-point values, if the value of x is NaN, NaN is returned. If the value of x is
positive or negative infinity, NaN is returned and errno is set to [EDOM].
If the correct result would cause underflow, 0.0 (zero) is returned.
ERRORS
If any of the following conditions occurs, the cos() function sets errno to the corresponding
value:
[EDOM] The value of x is infinite.
RELATED INFORMATION
Functions: acos(3), acosh(3), asin(3), asinh(3), atan(3), atan2(3), atanh(3), cosh(3),
fp_class(3), isnan(3), sin(3), sinh(3), tan(3), tanh(3).
Files: float(4), math(4).
STANDARDS CONFORMANCE
This function conforms to the XPG4 Version 2 specification with extensions when used for IEEE
floating-point format data. This function conforms to the XPG4 Version 2 specification without
extensions when used for Tandem floating-point data.
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 values, errno is not set to [EDOM] when the value of x is NaN.
527192-007 Hewlett-Packard Company 1−43