copysign(3) [v7 man page]

COPYSIGN(3)						     Linux Programmer's Manual						       COPYSIGN(3)

NAME

       copysign, copysignf, copysignl - copy sign of a number

SYNOPSIS

       #include <math.h>

       double copysign(double x, double y);
       float copysignf(float x, float y);
       long double copysignl(long double x, long double y);

       Link with -lm.

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       copysign(), copysignf(), copysignl():
	   _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
	       || /* Since glibc 2.19: */ _DEFAULT_SOURCE
	       || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION

       These functions return a value whose absolute value matches that of x, but whose sign bit matches that of y.

       For example, copysign(42.0, -1.0) and copysign(-42.0, -1.0) both return -42.0.

RETURN VALUE

       On success, these functions return a value whose magnitude is taken from x and whose sign is taken from y.

       If x is a NaN, a NaN with the sign bit of y is returned.

ERRORS

       No errors occur.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       +-------------------------------------+---------------+---------+
       |Interface			     | Attribute     | Value   |
       +-------------------------------------+---------------+---------+
       |copysign(), copysignf(), copysignl() | Thread safety | MT-Safe |
       +-------------------------------------+---------------+---------+
CONFORMING TO

       C99, POSIX.1-2001, POSIX.1-2008.  This function is defined in IEC 559 (and the appendix with recommended functions in IEEE 754/IEEE 854).

NOTES

       On architectures where the floating-point formats are not IEEE 754 compliant, these functions may treat a negative zero as positive.

SEE ALSO

       signbit(3)

COLOPHON

       This  page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

GNU
								    2017-09-15							       COPYSIGN(3)

ieee_functions(3)					     Library Functions Manual						 ieee_functions(3)

NAME

       copysign, finite, fp_class, isnan, nextafter, unordered	- Related miscellaneous IEEE arithmetic functions.

LIBRARY

       Math Library (libm.a)

SYNOPSIS

       #include <math.h>

       double copysign	 (double x, double y); float  copysignf  (float  x, float  y); long double copysignl   (long double x, long double y); int
       finite	  (double x); int    finitef	(float	x); int    finitel     (long double x); int    fp_class    (double  x);  int	 fp_classf
       (float  x); int	  fp_classl   (long double x); int    isnan	 (double x); int    isnanf     (float  x); int	  isnanl      (long double
       x); double nextafter  (double x, double y); float  nextafterf (float  x, float  y); long double nextafterl  (long double x, long double y);
       int    unordered  (double x, double y); int    unorderedf (float  x, float  y); int    unorderedl  (long double x, long double y);

STANDARDS

       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.

DESCRIPTION

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

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

       The fp_class(), fp_classf(),  and fp_classl() functions determine the class of an IEEE floating-point value.  They return one of  the  con-
       stants  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:

       -----------------------------------------------------
       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 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(), isnanf(), and isnanl() 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(), nextafterf(), and nextafterl() functions return the next machine-representable number from x in the direction of y.

       The unordered(), unorderedf(), and unorderedl() 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)