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
84 If \fIx\fP equals \fIy\fP, the functions return \fIy\fP.
88 functions do the same as the
90 functions, except that they have a
95 these functions return the next representable floating-point value after
106 (cast to the same type as
121 and the result would overflow,
122 a range error occurs,
123 and the functions return
128 respectively, with the correct mathematical sign.
134 and the correct function result would be subnormal, zero, or underflow,
135 a range error occurs,
136 and either the correct value (if it can be represented),
141 for information on how to determine whether an error has occurred
142 when calling these functions.
144 The following errors can occur:
146 Range error: result overflow
147 .\" e.g., nextafter(DBL_MAX, HUGE_VAL);
151 An overflow floating-point exception
155 Range error: result is subnormal or underflows
156 .\" e.g., nextafter(DBL_MIN, 0.0);
160 An underflow floating-point exception
164 These functions do not set
166 .\" FIXME . Is it intentional that these functions do not set errno?
167 .\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6799
170 This function is defined in IEC 559 (and the appendix with
171 recommended functions in IEEE 754/IEEE 854).
173 In glibc version 2.5 and earlier, these functions do not raise an underflow
176 exception when an underflow occurs.