This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

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

       These functions may raise the inexact floating-point exception if the result differs in  value  from  the
       argument.

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for  Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

       Any typographical or formatting errors that appear in this page are most likely to have  been  introduced
       during   the   conversion  of  the  source  files  to  man  page  format.  To  report  such  errors,  see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                                   2017                                          CEIL(3POSIX)

       The  functionality  described  on  this  reference  page is aligned with the ISO C standard. Any conflict
       between the requirements described  here  and  the  ISO C  standard  is  unintentional.  This  volume  of
       POSIX.1‐2017 defers to the ISO C standard.

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

       No errors are defined.

       Thefollowingsectionsareinformative.

       None.

       None.

       ceil, ceilf, ceill — ceiling value function

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.

       None.

       The result shall have the same sign as x.

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

       If x is NaN, a NaN shall be returned.

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

feclearexcept(), fetestexcept(), floor(), isnan()

       The Base Definitions volume of POSIX.1‐2017, Section4.20, TreatmentofErrorConditionsforMathematicalFunctions, <math.h>

       #include <math.h>

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