1CEIL(P) POSIX Programmer's Manual CEIL(P)
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6 ceil, ceilf, ceill - ceiling value function
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9 #include <math.h>
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11 double ceil(double x);
12 float ceilf(float x);
13 long double ceill(long double x);
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17 These functions shall compute the smallest integral value not less than
18 x.
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20 An application wishing to check for error situations should set errno
21 to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these
22 functions. On return, if errno is non-zero or fetestexcept(FE_INVALID
23 | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has
24 occurred.
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27 Upon successful completion, ceil(), ceilf(), and ceill() shall return
28 the smallest integral value not less than x, expressed as a type dou‐
29 ble, float, or long double, respectively.
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31 If x is NaN, a NaN shall be returned.
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33 If x is ±0 or ±Inf, x shall be returned.
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35 If the correct value would cause overflow, a range error shall occur
36 and ceil(), ceilf(), and ceill() shall return the value of the macro
37 HUGE_VAL, HUGE_VALF, and HUGE_VALL, respectively.
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40 These functions shall fail if:
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42 Range Error
43 The result overflows.
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45 If the integer expression (math_errhandling & MATH_ERRNO) is non-zero,
46 then errno shall be set to [ERANGE]. If the integer expression
47 (math_errhandling & MATH_ERREXCEPT) is non-zero, then the overflow
48 floating-point exception shall be raised.
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51 The following sections are informative.
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54 None.
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57 The integral value returned by these functions need not be expressible
58 as an int or long. The return value should be tested before assigning
59 it to an integer type to avoid the undefined results of an integer
60 overflow.
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62 The ceil() function can only overflow when the floating-point represen‐
63 tation has DBL_MANT_DIG > DBL_MAX_EXP.
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65 On error, the expressions (math_errhandling & MATH_ERRNO) and
66 (math_errhandling & MATH_ERREXCEPT) are independent of each other, but
67 at least one of them must be non-zero.
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70 None.
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73 None.
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76 feclearexcept() , fetestexcept() , floor() , isnan() , the Base Defini‐
77 tions volume of IEEE Std 1003.1-2001, Section 4.18, Treatment of Error
78 Conditions for Mathematical Functions, <math.h>
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81 Portions of this text are reprinted and reproduced in electronic form
82 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
83 -- Portable Operating System Interface (POSIX), The Open Group Base
84 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
85 Electrical and Electronics Engineers, Inc and The Open Group. In the
86 event of any discrepancy between this version and the original IEEE and
87 The Open Group Standard, the original IEEE and The Open Group Standard
88 is the referee document. The original Standard can be obtained online
89 at http://www.opengroup.org/unix/online.html .
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93IEEE/The Open Group 2003 CEIL(P)