1CEIL(3P)                   POSIX Programmer's Manual                  CEIL(3P)
2
3
4

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.
10

NAME

12       ceil, ceilf, ceill - ceiling value function
13

SYNOPSIS

15       #include <math.h>
16
17       double ceil(double x);
18       float ceilf(float x);
19       long double ceill(long double x);
20
21

DESCRIPTION

23       These functions shall compute the smallest integral value not less than
24       x.
25
26       An  application  wishing to check for error situations should set errno
27       to zero and  call  feclearexcept(FE_ALL_EXCEPT)  before  calling  these
28       functions.   On return, if errno is non-zero or fetestexcept(FE_INVALID
29       | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error  has
30       occurred.
31

RETURN VALUE

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.
36
37       If x is NaN, a NaN shall be returned.
38
39       If x is ±0 or ±Inf, x shall be returned.
40
41       If  the  correct  value would cause overflow, a range error shall occur
42       and ceil(), ceilf(), and ceill() shall return the value  of  the  macro
43       HUGE_VAL, HUGE_VALF, and HUGE_VALL, respectively.
44

ERRORS

46       These functions shall fail if:
47
48       Range Error
49              The result overflows.
50
51       If  the integer expression (math_errhandling & MATH_ERRNO) is non-zero,
52       then errno  shall  be  set  to  [ERANGE].  If  the  integer  expression
53       (math_errhandling  &  MATH_ERREXCEPT)  is  non-zero,  then the overflow
54       floating-point exception shall be raised.
55
56
57       The following sections are informative.
58

EXAMPLES

60       None.
61

APPLICATION USAGE

63       The integral value returned by these functions need not be  expressible
64       as  an  int or long. The return value should be tested before assigning
65       it to an integer type to avoid the  undefined  results  of  an  integer
66       overflow.
67
68       The ceil() function can only overflow when the floating-point represen‐
69       tation has DBL_MANT_DIG > DBL_MAX_EXP.
70
71       On  error,  the  expressions  (math_errhandling   &   MATH_ERRNO)   and
72       (math_errhandling  & MATH_ERREXCEPT) are independent of each other, but
73       at least one of them must be non-zero.
74

RATIONALE

76       None.
77

FUTURE DIRECTIONS

79       None.
80

SEE ALSO

82       feclearexcept(), fetestexcept(), floor(), isnan(), the Base Definitions
83       volume of IEEE Std 1003.1-2001, Section 4.18, Treatment of Error Condi‐
84       tions for Mathematical Functions, <math.h>
85

87       Portions of this text are reprinted and reproduced in  electronic  form
88       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
89       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
90       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
91       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
92       event of any discrepancy between this version and the original IEEE and
93       The Open Group Standard, the original IEEE and The Open Group  Standard
94       is  the  referee document. The original Standard can be obtained online
95       at http://www.opengroup.org/unix/online.html .
96
97
98
99IEEE/The Open Group                  2003                             CEIL(3P)
Impressum