1 .\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
2 .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
3 .\" <mtk.manpages@gmail.com>
5 .\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
6 .\" Distributed under GPL
9 .\" Based on glibc infopages
11 .TH NEXTAFTER 3 2010-09-20 "GNU" "Linux Programmer's Manual"
13 nextafter, nextafterf, nextafterl, nexttoward, nexttowardf, nexttowardl \-
14 floating-point number manipulation
18 .BI "double nextafter(double " x ", double " y );
20 .BI "float nextafterf(float " x ", float " y );
22 .BI "long double nextafterl(long double " x ", long double " y );
24 .BI "double nexttoward(double " x ", long double " y );
26 .BI "float nexttowardf(float " x ", long double " y );
28 .BI "long double nexttowardl(long double " x ", long double " y );
33 Feature Test Macro Requirements for glibc (see
34 .BR feature_test_macros (7)):
40 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 500 ||
41 _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED ||
43 _POSIX_C_SOURCE\ >=\ 200112L;
52 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
53 _POSIX_C_SOURCE\ >=\ 200112L;
63 _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
64 _POSIX_C_SOURCE\ >=\ 200112L;
73 functions return the next representable floating-point value following
81 these functions will return the largest representable number less than
93 functions do the same as the
95 functions, except that they have a
100 these functions return the next representable floating-point value after
111 (cast to the same type as
126 and the result would overflow,
127 a range error occurs,
128 and the functions return
133 respectively, with the correct mathematical sign.
139 and the correct function result would be subnormal, zero, or underflow,
140 a range error occurs,
141 and either the correct value (if it can be represented),
146 for information on how to determine whether an error has occurred
147 when calling these functions.
149 The following errors can occur:
151 Range error: result overflow
152 .\" e.g., nextafter(DBL_MAX, HUGE_VAL);
156 An overflow floating-point exception
160 Range error: result is subnormal or underflows
161 .\" e.g., nextafter(DBL_MIN, 0.0);
165 An underflow floating-point exception
169 These functions do not set
171 .\" FIXME . Is it intentional that these functions do not set errno?
172 .\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6799
175 This function is defined in IEC 559 (and the appendix with
176 recommended functions in IEEE 754/IEEE 854).
178 In glibc version 2.5 and earlier, these functions do not raise an underflow
181 exception when an underflow occurs.