Index for Section 3

Alphabetical listing for I

Bottom of page

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), copysignf(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 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:

  _____________________________________________________
  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

Index for Section 3

Alphabetical listing for I

Top of page