1SIGNBIT(3P)                POSIX Programmer's Manual               SIGNBIT(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

12       signbit — test sign
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SYNOPSIS

15       #include <math.h>
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17       int signbit(real-floating x);
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DESCRIPTION

20       The functionality described on this reference page is aligned with  the
21       ISO C  standard.  Any  conflict between the requirements described here
22       and the ISO C standard is unintentional. This  volume  of  POSIX.1‐2017
23       defers to the ISO C standard.
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25       The  signbit()  macro  shall determine whether the sign of its argument
26       value is negative. NaNs, zeros, and infinities have a sign bit.
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RETURN VALUE

29       The signbit() macro shall return a non-zero value if and  only  if  the
30       sign of its argument value is negative.
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ERRORS

33       No errors are defined.
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35       The following sections are informative.
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EXAMPLES

38       None.
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APPLICATION USAGE

41       None.
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RATIONALE

44       None.
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FUTURE DIRECTIONS

47       None.
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SEE ALSO

50       fpclassify(), isfinite(), isinf(), isnan(), isnormal()
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52       The Base Definitions volume of POSIX.1‐2017, <math.h>
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55       Portions  of  this text are reprinted and reproduced in electronic form
56       from IEEE Std 1003.1-2017, Standard for Information Technology --  Por‐
57       table  Operating System Interface (POSIX), The Open Group Base Specifi‐
58       cations Issue 7, 2018 Edition, Copyright (C) 2018 by the  Institute  of
59       Electrical  and  Electronics Engineers, Inc and The Open Group.  In the
60       event of any discrepancy between this version and the original IEEE and
61       The  Open Group Standard, the original IEEE and The Open Group Standard
62       is the referee document. The original Standard can be  obtained  online
63       at http://www.opengroup.org/unix/online.html .
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65       Any  typographical  or  formatting  errors that appear in this page are
66       most likely to have been introduced during the conversion of the source
67       files  to  man page format. To report such errors, see https://www.ker‐
68       nel.org/doc/man-pages/reporting_bugs.html .
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72IEEE/The Open Group                  2017                          SIGNBIT(3P)
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