Manpage of CEIL

CEIL

Section: Linux Programmer's Manual (3)
Updated: 2016-03-15
Index
 

NAME

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

SYNOPSIS

#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
 

DESCRIPTION

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.  

RETURN VALUE

These functions return the ceiling of x.

If xis integral, +0, -0, NaN, or infinite, xitself is returned.  

ERRORS

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

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).
InterfaceAttributeValue
ceil(), ceilf(), ceill() Thread safetyMT-Safe
 

CONFORMING TO

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

The variant returning doublealso conforms to SVr4, 4.3BSD, C89.  

NOTES

SUSv2 and POSIX.1-2001 contain text about overflow (which might set errnoto ERANGE, or raise an FE_OVERFLOWexception). 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.  

SEE ALSO

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


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
ATTRIBUTES
CONFORMING TO
NOTES
SEE ALSO

This document was created by man2html, using the manual pages.
Time: 22:27:58 GMT, June 20, 2016 Click Here!