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NAME
       ceil, ceilf, ceill - ceiling value function


SYNOPSIS
       #include <math.h>

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


DESCRIPTION
       These functions shall compute the smallest integral value not less than x.

       An  application  wishing  to  check for error situations should set errno to zero and call
       feclearexcept(FE_ALL_EXCEPT) before calling these functions.  On return, if errno is  non-
       zero  or fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero,
       an error has occurred.


RETURN VALUE
       Upon successful completion,  ceil(),  ceilf(),  and  ceill()  shall  return  the  smallest
       integral  value  not  less  than  x,  expressed  as  a type double, float, or long double,
       respectively.

       If x is NaN, a NaN shall be returned.

       If x is ±0 or ±Inf, x shall be returned.

       If the correct value would cause overflow, a range error shall occur and ceil(),  ceilf(),
       and  ceill()  shall  return  the  value  of  the macro HUGE_VAL, HUGE_VALF, and HUGE_VALL,
       respectively.


ERRORS
       These functions shall fail if:

       Range Error
              The result overflows.

       If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be
       set  to  [ERANGE].  If  the integer expression (math_errhandling & MATH_ERREXCEPT) is non-
       zero, then the overflow floating-point exception shall be raised.

       The following sections are informative.


EXAMPLES
       None.


APPLICATION USAGE
       The integral value returned by these functions need not be expressible as an int or  long.
       The  return  value  should  be  tested before assigning it to an integer type to avoid the
       undefined results of an integer overflow.

       The  ceil()  function  can  only  overflow  when  the  floating-point  representation  has
       DBL_MANT_DIG > DBL_MAX_EXP.

       On  error,  the  expressions  (math_errhandling  &  MATH_ERRNO)  and  (math_errhandling  &
       MATH_ERREXCEPT) are independent of each other, but at least one of them must be non-zero.


RATIONALE
       None.


FUTURE DIRECTIONS
       None.


SEE ALSO
       feclearexcept() , fetestexcept() , floor() , isnan() ,  the  Base  Definitions  volume  of
       IEEE Std 1003.1-2001,  Section  4.18,  Treatment  of  Error  Conditions  for  Mathematical
       Functions, <math.h>


COPYRIGHT
       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2003  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003  by
       the  Institute  of  Electrical  and  Electronics Engineers, Inc and The Open Group. In the
       event of any discrepancy between this version and the original IEEE  and  The  Open  Group
       Standard,  the  original  IEEE  and  The  Open Group Standard is the referee document. The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .