man3/nextafter.3

   1 .\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
   2 .\" Distributed under GPL
   3 .\" Based on glibc infopages
   4 .TH NEXTAFTER 3 2002-08-10 "GNU" "libc math functions"
   5 .SH NAME
   6 nextafter, nextafterf, nextafterl, nexttoward, nexttowardf, nexttowardl \-
   7 floating point number manipulation
   8 .SH SYNOPSIS
   9 .B #include <math.h>
  10 .sp
  11 .BI "double nextafter(double " x ", double " y );
  12 .br
  13 .BI "float nextafterf(float " x ", float " y );
  14 .br
  15 .BI "long double nextafterl(long double " x ", long double " y );
  16 .sp
  17 .BI "double nexttoward(double " x ", long double " y );
  18 .br
  19 .BI "float nexttowardf(float " x ", long double " y );
  20 .br
  21 .BI "long double nexttowardl(long double " x ", long double " y );
  22 .sp
  23 Link with \-lm.
  24 .SH DESCRIPTION
  25 The
  26 .BR nextafter ()
  27 functions return the next representable neighbor of
  28 \fIx\fP in the direction towards \fIy\fP.
  29 The size of the step
  30 between \fIx\fP and the result depends on the type of the result.
  31 If \fIx\fP = \fIy\fP the function simply returns \fIy\fP.
  32 If either value is
  33 .IR NaN ,
  34 then
  35 .I NaN
  36 is returned.
  37 Otherwise a value corresponding to the value of the
  38 least significant bit in the mantissa is added or subtracted,
  39 depending on the direction.
  40 .PP
  41 The
  42 .BR nexttoward ()
  43 functions do the same as the
  44 .BR nextafter ()
  45 functions, except that they have a long double second argument.
  46 .PP
  47 These functions will signal overflow or underflow if the result
  48 goes outside of the range of normalized numbers.
  49 .SH "CONFORMING TO"
  50 C99.
  51 This function is defined in IEC 559 (and the appendix with
  52 recommended functions in IEEE 754/IEEE 854).
  53 .SH "SEE ALSO"
  54 .BR nearbyint (3)