2004-11-03 13:51:07 +00:00
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.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
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2008-08-01 05:26:35 +00:00
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.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
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.\" <mtk.manpages@gmail.com>
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2004-11-03 13:51:07 +00:00
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.\" Distributed under GPL
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.\" Based on glibc infopages
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_exit.2, brk.2, capget.2, chdir.2, chmod.2, chown.2, chroot.2, getdtablesize.2, gethostname.2, getpagesize.2, getsid.2, killpg.2, mknod.2, mknodat.2, poll.2, posix_fadvise.2, pread.2, readlink.2, setpgid.2, setreuid.2, sigaltstack.2, stat.2, symlink.2, sync.2, truncate.2, vfork.2, wait.2, wait4.2, a64l.3, abs.3, acos.3, acosh.3, asin.3, asinh.3, atan.3, atan2.3, atoi.3, cbrt.3, ceil.3, copysign.3, cosh.3, dirfd.3, div.3, ecvt.3, erf.3, erfc.3, exp.3, exp2.3, fabs.3, fdim.3, ffs.3, floor.3, fma.3, fmax.3, fmin.3, fmod.3, fpclassify.3, frexp.3, ftw.3, fwide.3, gcvt.3, getcwd.3, getdate.3, getgrent.3, gethostid.3, getpass.3, getpwent.3, getsubopt.3, getw.3, hypot.3, ilogb.3, index.3, isalpha.3, isgreater.3, iswblank.3, j0.3, ldexp.3, lockf.3, log.3, log10.3, log1p.3, logb.3, lrint.3, lround.3, mkstemp.3, mktemp.3, modf.3, mq_receive.3, mq_send.3, nan.3, nextafter.3, posix_fallocate.3, posix_memalign.3, printf.3, qecvt.3, random.3, realpath.3, remainder.3, remquo.3, rint.3, round.3, scalb.3, scalbln.3, scanf.3, siginterrupt.3, signbit.3, sigset.3, sinh.3, sqrt.3, strcasecmp.3, strcat.3, strchr.3, strcmp.3, strcoll.3, strcpy.3, strfry.3, strpbrk.3, strsep.3, strspn.3, strstr.3, strtod.3, strtok.3, strtol.3, strtoul.3, strxfrm.3, tanh.3, tgamma.3, trunc.3, ttyslot.3, ualarm.3, usleep.3, wprintf.3, armscii-8.7, cp1251.7, iso_8859-10.7, iso_8859-11.7, iso_8859-13.7, iso_8859-14.7, iso_8859-3.7, iso_8859-5.7, iso_8859-6.7, iso_8859-8.7, koi8-u.7: tstamp
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2010-09-19 17:19:13 +00:00
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.TH NEXTAFTER 3 2010-09-20 "GNU" "Linux Programmer's Manual"
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2004-11-03 13:51:07 +00:00
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.SH NAME
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2007-04-12 22:42:49 +00:00
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nextafter, nextafterf, nextafterl, nexttoward, nexttowardf, nexttowardl \-
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floating-point number manipulation
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2004-11-03 13:51:07 +00:00
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.SH SYNOPSIS
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.B #include <math.h>
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.sp
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.BI "double nextafter(double " x ", double " y );
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.br
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.BI "float nextafterf(float " x ", float " y );
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.br
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.BI "long double nextafterl(long double " x ", long double " y );
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.sp
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.BI "double nexttoward(double " x ", long double " y );
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.br
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.BI "float nexttowardf(float " x ", long double " y );
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.br
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2007-04-12 22:42:49 +00:00
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.BI "long double nexttowardl(long double " x ", long double " y );
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.sp
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2007-07-21 05:25:03 +00:00
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Link with \fI\-lm\fP.
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2007-07-08 12:11:40 +00:00
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.sp
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.in -4n
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Feature Test Macro Requirements for glibc (see
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.BR feature_test_macros (7)):
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.in
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.sp
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.ad l
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.BR nextafter ():
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2010-09-18 15:03:40 +00:00
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.RS 4
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_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 500 ||
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_XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED ||
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_ISOC99_SOURCE ||
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_POSIX_C_SOURCE\ >=\ 200112L;
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.br
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or
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.I cc\ -std=c99
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2010-09-18 15:03:40 +00:00
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.RE
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2008-08-01 05:26:35 +00:00
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.br
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.BR nextafterf (),
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.BR nextafterl ():
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.RS 4
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_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
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_POSIX_C_SOURCE\ >=\ 200112L;
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.br
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or
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.I cc\ -std=c99
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.RE
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.br
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.BR nexttoward (),
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.BR nexttowardf (),
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.BR nexttowardl ():
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.RS 4
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2010-09-18 15:07:40 +00:00
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_XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
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_POSIX_C_SOURCE\ >=\ 200112L;
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2010-09-18 15:03:40 +00:00
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.br
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or
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.I cc\ -std=c99
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2010-09-18 15:03:40 +00:00
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.RE
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.ad b
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.SH DESCRIPTION
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The
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.BR nextafter ()
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functions return the next representable floating-point value following
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.I x
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in the direction of
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.IR y .
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If
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.I y
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is less than
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.IR x ,
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these functions will return the largest representable number less than
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.IR x .
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If \fIx\fP equals \fIy\fP, the functions return \fIy\fP.
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The
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.BR nexttoward ()
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functions do the same as the
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.BR nextafter ()
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functions, except that they have a
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.I "long double"
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second argument.
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.SH RETURN VALUE
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On success,
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these functions return the next representable floating-point value after
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.I x
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in the direction of
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.IR y .
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If
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.I x
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equals
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.IR y ,
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then
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.I y
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(cast to the same type as
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.IR x )
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is returned.
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If
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.I x
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or
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.I y
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is a NaN,
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a NaN is returned.
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If
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.I x
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is finite,
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.\" e.g., DBL_MAX
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and the result would overflow,
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a range error occurs,
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and the functions return
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.BR HUGE_VAL ,
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.BR HUGE_VALF ,
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or
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.BR HUGE_VALL ,
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respectively, with the correct mathematical sign.
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If
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.I x
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is not equal to
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.IR y ,
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and the correct function result would be subnormal, zero, or underflow,
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a range error occurs,
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and either the correct value (if it can be represented),
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or 0.0, is returned.
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.SH ERRORS
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See
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.BR math_error (7)
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for information on how to determine whether an error has occurred
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when calling these functions.
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.PP
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The following errors can occur:
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.TP
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Range error: result overflow
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.\" e.g., nextafter(DBL_MAX, HUGE_VAL);
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.\" .I errno
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.\" is set to
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.\" .BR ERANGE .
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An overflow floating-point exception
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.RB ( FE_OVERFLOW )
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is raised.
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.TP
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Range error: result is subnormal or underflows
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.\" e.g., nextafter(DBL_MIN, 0.0);
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.\" .I errno
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.\" is set to
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.\" .BR ERANGE .
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An underflow floating-point exception
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.RB ( FE_UNDERFLOW )
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is raised.
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.PP
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These functions do not set
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.IR errno .
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.\" FIXME . Is it intentional that these functions do not set errno?
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.\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6799
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.SH "CONFORMING TO"
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C99, POSIX.1-2001.
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2007-04-24 16:44:51 +00:00
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This function is defined in IEC 559 (and the appendix with
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recommended functions in IEEE 754/IEEE 854).
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2008-08-10 19:20:27 +00:00
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.SH BUGS
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In glibc version 2.5 and earlier, these functions do not raise an underflow
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floating-point
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.RB ( FE_UNDERFLOW )
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exception when an underflow occurs.
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2004-11-03 13:51:07 +00:00
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.SH "SEE ALSO"
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.BR nearbyint (3)
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