# ceil(3p) [posix man page]

CEIL(3P) POSIX Programmer's Manual CEIL(3P)PROLOG

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

ceil, ceilf, ceillceiling value function--SYNOPSIS

#include <math.h> double ceil(double x); float ceilf(float x); long double ceill(long double x);DESCRIPTION

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.1-2008 defers to the ISO C standard. These functions shall compute the smallest integral value not less than x.RETURN VALUE

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 dou- ble, float, or long double, respectively. If x is NaN, a NaN shall be returned. If x is +-0 or +-Inf, x shall be returned.ERRORS

No errors are defined. The following sections are informative.EXAMPLES

None.APPLICATION USAGE

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.RATIONALE

None.FUTURE DIRECTIONS

None.SEE ALSO

feclearexcept(), fetestexcept(), floor(), isnan() The Base Definitions volume of POSIX.1-2008, Section 4.19, 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, 2013 Edition, Standard for Information Technol- ogyPortable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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 Stan- dard is the referee document. The original Standard can be obtained online at http://www.unix.org/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 2013 CEIL(3P)

## Check Out this Related Man Page

CEIL(3P) POSIX Programmer's Manual CEIL(3P)PROLOG

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

ceil, ceilf, ceill - ceiling value functionSYNOPSIS

#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 dou- ble, 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 assign- ing 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 Technol- ogyPortable 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 .--IEEE

/The Open Group 2003 CEIL(3P)