Content-type: text/html Man page of ieee_functions


Section: C Library Functions (3)
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copysign, finite, fp_class, isnan, nextafter, unordered - Appendix and related miscellaneous functions for IEEE arithmetic  


Math Library (libm.a)  


#include <math.h>

double copysign (double x, double y); float copysignf (float x, float y); int finite (double x); int finitef (float x); int fp_class (double x); int fp_classf (float x); int isnan (double x); int isnanf (float x); double nextafter (double x, double y); float nextafterf (float x, float y); int unordered (double x, double y); int unorderedf (float x, float y);  


Interfaces documented on this reference page conform to industry standards as follows:

isnan(): XPG4

nextafter(): XPG4-UNIX

Refer to the standards(5) reference page for more information about industry standards and associated tags.  


The copysign() and copysignf() functions return x with the same sign as y. IEEE 754 requires copysign(x,NaN) and copysignf(x,NaN) to return +x or -x.

The finite() and finitef() functions return the integer value 1 (True) or 0 (False). The finite(x) and finitef(x) functions return 1 when -infinity < x < +infinity. They return 0 when |x| = infinity or x is a NaN.

The fp_class() and fp_classf() functions determine the class of IEEE floating-point values. They return one of the constants in the file <fp_class.h> and never cause an exception, even for signaling NaNs. These routines implement the recommended function class(x) in the appendix of the IEEE 754-1985 standard for binary floating-point arithmetic. The constants in <fp_class.h> refer to the following classes of values:


FP_SNAN Signaling NaN (Not-a-Number)       
FP_QNAN Quiet NaN (Not-a-Number)
FP_POS_INF +infinity
FP_NEG_INF -infinity
FP_POS_NORM Positive normalized
FP_NEG_NORM Negative normalized
FP_POS_DENORM Positive denormalized
FP_NEG_DENORM Negative denormalized
FP_POS_ZERO +0.0 (positive zero)
FP_NEG_ZERO -0.0 (negative zero)

The isnan() and isnanf() functions return the value 1
(True) if x is NaN (the IEEE floating point reserved not-a-number value); otherwise, it returns the value 0 (False).

The nextafter() and nextafterf() functions return the next machine-representable number from x in the direction of y.

The unordered() and unorderedf() functions return the value 1 (True) if either x or y or both is a NaN; otherwise, it returns the value 0 (False).  


drem(3), logb(3), scalb(3), rint(3), sqrt(3), and ANSI/IEEE Std 754-1985, IEEE Standard for Binary Floating-Point Arithmetic delim off




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Time: 02:42:10 GMT, October 02, 2010