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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.\" Distributed under GPL
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.\" Based on glibc infopages
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.\"
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.\" Corrections by aeb
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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 NAN 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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nan, nanf, nanl \- return 'Not a Number'
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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 nan(const char *" tagp );
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2004-11-11 17:28:42 +00:00
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.br
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2004-11-03 13:51:07 +00:00
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.BI "float nanf(const char *" tagp );
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2004-11-11 17:28:42 +00:00
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.br
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2004-11-03 13:51:07 +00:00
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.BI "long double nanl(const char *" tagp );
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.sp
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2008-07-23 13:04:35 +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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2010-09-18 15:42:09 +00:00
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.ad l
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2007-07-08 12:11:40 +00:00
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.BR nan (),
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2007-07-08 12:39:24 +00:00
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.BR nanf (),
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2007-07-08 12:11:40 +00:00
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.BR nanl ():
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2010-09-18 15:40:50 +00:00
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.RS 4
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2010-09-18 15:42:09 +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 15:40:50 +00:00
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.br
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or
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2007-07-08 12:11:40 +00:00
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.I cc\ -std=c99
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2010-09-18 15:40:50 +00:00
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.RE
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2010-09-18 15:42:09 +00:00
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.ad
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2004-11-03 13:51:07 +00:00
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.SH DESCRIPTION
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These functions return a representation (determined by
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.IR tagp )
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2007-04-24 16:44:51 +00:00
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of a quiet NaN.
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If the implementation does not support
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2004-11-03 13:51:07 +00:00
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quiet NaNs, these functions return zero.
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.LP
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The call
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.I nan("char-sequence")
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2008-07-25 18:44:28 +00:00
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is equivalent to:
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.nf
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strtod("NAN(char-sequence)", NULL);
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.fi
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.PP
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Similarly, calls to
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2005-11-02 11:34:24 +00:00
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.BR nanf ()
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2004-11-03 13:51:07 +00:00
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and
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2005-11-02 11:34:24 +00:00
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.BR nanl ()
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2004-11-03 13:51:07 +00:00
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are equivalent to analogous calls to
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2007-05-12 00:30:29 +00:00
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.BR strtof (3)
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2004-11-03 13:51:07 +00:00
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and
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2007-05-12 00:30:29 +00:00
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.BR strtold (3).
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2004-11-03 13:51:07 +00:00
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.PP
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The argument
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.I tagp
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2007-04-12 22:42:49 +00:00
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is used in an unspecified manner.
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On IEEE 754 systems, there are many representations of NaN, and
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2004-11-03 13:51:07 +00:00
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.I tagp
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2007-04-12 22:42:49 +00:00
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selects one.
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On other systems it may do nothing.
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2008-08-11 17:13:47 +00:00
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.SH VERSIONS
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These functions first appeared in glibc in version 2.1.
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2004-11-03 13:51:07 +00:00
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.SH "CONFORMING TO"
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2008-07-25 20:21:06 +00:00
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C99, POSIX.1-2001.
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2007-04-24 16:44:51 +00:00
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See also IEC 559 and the appendix with
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2004-11-03 13:51:07 +00:00
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recommended functions in IEEE 754/IEEE 854.
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.SH "SEE ALSO"
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.BR isnan (3),
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2008-07-23 13:04:35 +00:00
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.BR strtod (3),
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.BR math_error (7)
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