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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 .