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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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LLROUND(3P) POSIX Programmer's Manual LLROUND(3P)
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.
llround, llroundf, llroundl — round to nearest integer value
#include <math.h>
long long llround(double x);
long long llroundf(float x);
long long llroundl(long double x);
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 round their argument to the nearest integer
value, rounding halfway cases away from zero, regardless of the
current rounding direction.
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.
Upon successful completion, these functions shall return the
rounded integer value.
If x is NaN, a domain error shall occur, and an unspecified value
is returned.
If x is +Inf, a domain error shall occur and an unspecified value
is returned.
If x is -Inf, a domain error shall occur and an unspecified value
is returned.
If the correct value is positive and too large to represent as a
long long, an unspecified value shall be returned. On systems
that support the IEC 60559 Floating-Point option, a domain error
shall occur; otherwise, a domain error may occur.
If the correct value is negative and too large to represent as a
long long, an unspecified value shall be returned. On systems
that support the IEC 60559 Floating-Point option, a domain error
shall occur; otherwise, a domain error may occur.
These functions shall fail if:
Domain Error
The x argument is NaN or ±Inf, or the correct value
is not representable as an integer.
If the integer expression (math_errhandling &
MATH_ERRNO) is non-zero, then errno shall be set to
[EDOM]. If the integer expression (math_errhandling
& MATH_ERREXCEPT) is non-zero, then the invalid
floating-point exception shall be raised.
These functions may fail if:
Domain Error
The correct value is not representable as an integer.
If the integer expression (math_errhandling &
MATH_ERRNO) is non-zero, then errno shall be set to
[EDOM]. If the integer expression (math_errhandling
& MATH_ERREXCEPT) is non-zero, then the invalid
floating-point exception shall be raised.
The following sections are informative.
None.
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.
These functions differ from the llrint() functions in that the
default rounding direction for the llround() functions round
halfway cases away from zero and need not raise the inexact
floating-point exception for non-integer arguments that round to
within the range of the return type.
None.
feclearexcept(3p), fetestexcept(3p), lround(3p)
The Base Definitions volume of POSIX.1‐2017, Section 4.20,
Treatment of Error Conditions for Mathematical Functions,
math.h(0p)
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 LLROUND(3P)
Pages that refer to this page: math.h(0p), lround(3p)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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