1CEIL(3P)                   POSIX Programmer's Manual                  CEIL(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       ceil, ceilf, ceill — ceiling value function
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SYNOPSIS

15       #include <math.h>
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17       double ceil(double x);
18       float ceilf(float x);
19       long double ceill(long double x);
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DESCRIPTION

22       The functionality described on this reference page is aligned with  the
23       ISO C  standard.  Any  conflict between the requirements described here
24       and the ISO C standard is unintentional. This  volume  of  POSIX.1‐2017
25       defers to the ISO C standard.
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27       These functions shall compute the smallest integral value not less than
28       x.
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RETURN VALUE

31       The result shall have the same sign as x.
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33       Upon successful completion, ceil(), ceilf(), and ceill()  shall  return
34       the  smallest  integral value not less than x, expressed as a type dou‐
35       ble, float, or long double, respectively.
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37       If x is NaN, a NaN shall be returned.
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39       If x is ±0 or ±Inf, x shall be returned.
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ERRORS

42       No errors are defined.
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44       The following sections are informative.
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EXAMPLES

47       None.
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APPLICATION USAGE

50       The integral value returned by these functions need not be  expressible
51       as  an intmax_t.  The return value should be tested before assigning it
52       to an integer type to avoid the undefined results of an  integer  over‐
53       flow.
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55       These  functions  may raise the inexact floating-point exception if the
56       result differs in value from the argument.
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RATIONALE

59       None.
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FUTURE DIRECTIONS

62       None.
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SEE ALSO

65       feclearexcept(), fetestexcept(), floor(), isnan()
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67       The Base Definitions volume of POSIX.1‐2017, Section 4.20, Treatment of
68       Error Conditions for Mathematical Functions, <math.h>
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71       Portions  of  this text are reprinted and reproduced in electronic form
72       from IEEE Std 1003.1-2017, Standard for Information Technology --  Por‐
73       table  Operating System Interface (POSIX), The Open Group Base Specifi‐
74       cations Issue 7, 2018 Edition, Copyright (C) 2018 by the  Institute  of
75       Electrical  and  Electronics Engineers, Inc and The Open Group.  In the
76       event of any discrepancy between this version and the original IEEE and
77       The  Open Group Standard, the original IEEE and The Open Group Standard
78       is the referee document. The original Standard can be  obtained  online
79       at http://www.opengroup.org/unix/online.html .
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81       Any  typographical  or  formatting  errors that appear in this page are
82       most likely to have been introduced during the conversion of the source
83       files  to  man page format. To report such errors, see https://www.ker‐
84       nel.org/doc/man-pages/reporting_bugs.html .
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88IEEE/The Open Group                  2017                             CEIL(3P)
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