NAME

fpclassify(), fpclassifyf() − floating-point operand classification functions

SYNOPSIS

#include <math.h>

int fpclassify(double x);

int fpclassifyf(float x);

DESCRIPTION

fpclassify() and fpclassifyf() return a non-negative integer value that specifies the IEEE operand class to which the argument x belongs.  The value returned is one of the following macros which are defined in <math.h>:

#define FP_PLUS_NORM      0  /* Positive normalized */
#define FP_MINUS_NORM     1  /* Negative normalized */
#define FP_PLUS_ZERO      2  /* Positive zero */
#define FP_MINUS_ZERO     3  /* Negative zero */
#define FP_PLUS_INF       4  /* Positive infinity */
#define FP_MINUS_INF      5  /* Negative infinity */
#define FP_PLUS_DENORM    6  /* Positive denormalized */
#define FP_MINUS_DENORM   7  /* Negative denormalized */
#define FP_SNAN           8  /* Signalling NaN */
#define FP_QNAN           9  /* Quiet NaN */

Every possible argument value falls into one of these ten categories, so these functions never result in an error. 

fpclassifyf() is the float version of fpclassify().  Programs must be compiled in ANSI mode (with the -Aa option) in order to use this function; otherwise, the compiler promotes the float argument to double, and the function returns incorrect results. 

DEPENDENCIES

Series 300/400

fpclassify() and fpclassifyf() are not supported on Series 300/400 systems. 

Series 700/800

fpclassify() and fpclassifyf() are provided in the PA1.1 versions of the math library only.  The +DA1.1 option (default on Series 700 systems) links in a PA1.1 version automatically.  A PA1.1 library can also be linked in explicitly.  For more information, see the HP-UX Floating-Point Guide.

These functions are not specified by any standard.  However, they implement the class() function suggested in the "Recommended Functions and Predicates" appendix of the IEEE -754 floating-point standard.  Also, fpclassifyf() is named in accordance with the conventions specified in the
 "Future Library Directions" section of the ANSI C standard. 

SEE ALSO

isnan(3M), isinf(3M), ieee(3M). 
 

Hewlett-Packard Company  —  HP-UX Release 9.0: August 1992