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       ceil, ceilf, ceill - ceiling function: smallest integral value not less than argument


       #include <math.h>

       double ceil(double x);
       float ceilf(float x);
       long double ceill(long double x);

       Link with -lm.

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       ceilf(), ceill():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE


       These functions return the smallest integral value that is not less than x.

       For example, ceil(0.5) is 1.0, and ceil(-0.5) is 0.0.


       These functions return the ceiling of x.

       If x is integral, +0, -0, NaN, or infinite, x itself is returned.


       No errors occur.  POSIX.1-2001 documents a range error for overflows, but see NOTES.


       For an explanation of the terms used in this section, see attributes(7).

       │InterfaceAttributeValue   │
       │ceil(), ceilf(), ceill() │ Thread safety │ MT-Safe │


       C99, POSIX.1-2001, POSIX.1-2008.

       The variant returning double also conforms to SVr4, 4.3BSD, C89.


       SUSv2  and  POSIX.1-2001  contain text about overflow (which might set errno to ERANGE, or
       raise an FE_OVERFLOW exception).  In practice, the result cannot overflow on  any  current
       machine,  so  this  error-handling  stuff is just nonsense.  (More precisely, overflow can
       happen only when the maximum value of the exponent is smaller than the number of  mantissa
       bits.   For  the  IEEE-754  standard  32-bit and 64-bit floating-point numbers the maximum
       value of the exponent is 128 (respectively, 1024), and the number of mantissa bits  is  24
       (respectively, 53).)

       The  integral  value  returned  by these functions may be too large to store in an integer
       type (int, long, etc.).  To avoid an overflow, which will produce  undefined  results,  an
       application  should  perform a range check on the returned value before assigning it to an
       integer type.


       floor(3), lrint(3), nearbyint(3), rint(3), round(3), trunc(3)


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                                            2017-09-15                                    CEIL(3)