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ieee_functions(3) Library Functions Manual ieee_functions(3) NAME copysign, finite, fp_class, isnan, nextafter, unordered - Appendix and related miscellaneous functions for IEEE arithmetic LIBRARY Math Library (libm.a) SYNOPSIS #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 is- nan (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); STANDARDS Interfaces documented on this reference page conform to industry stan- dards as follows: isnan(): XPG4 nextafter(): XPG4-UNIX Refer to the standards(5) reference page for more information about in- dustry standards and associated tags. DESCRIPTION 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 ap- pendix of the IEEE 754-1985 standard for binary floating-point arith- metic. The constants in <fp_class.h> refer to the following classes of values: tab(@); lfHB lfHB lfHB l l l . _ Constant@Class@ _ 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 nor- malized @ 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-rep- resentable 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). RELATED INFORMATION 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 ieee_functions(3)