PROLOG  NAME  SYNOPSIS  DESCRIPTION  RETURN VALUE  ERRORS  EXAMPLES  APPLICATION USAGE  RATIONALE  FUTURE DIRECTIONS  SEE ALSO  COPYRIGHT 

LRINT(3P) POSIX Programmer's Manual LRINT(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.
lrint, lrintf, lrintl — round to nearest integer value using current rounding direction
#include <math.h> long lrint(double x); long lrintf(float x); long lrintl(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.1‐2008 defers to the ISO C standard. These functions shall round their argument to the nearest integer value, rounding according to 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 nonzero or fetestexcept(FE_INVALID  FE_DIVBYZERO  FE_OVERFLOW  FE_UNDERFLOW) is nonzero, 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, an unspecified value shall be returned. On systems that support the IEC 60559 FloatingPoint 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, an unspecified value shall be returned. On systems that support the IEC 60559 FloatingPoint 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 nonzero, then errno shall be set to [EDOM]. If the integer expression (math_errhandling & MATH_ERREXCEPT) is nonzero, then the invalid floatingpoint 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 nonzero, then errno shall be set to [EDOM]. If the integer expression (math_errhandling & MATH_ERREXCEPT) is nonzero, then the invalid floatingpoint 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 nonzero.
These functions provide floatingtointeger conversions. They round according to the current rounding direction. If the rounded value is outside the range of the return type, the numeric result is unspecified and the invalid floatingpoint exception is raised. When they raise no other floatingpoint exception and the result differs from the argument, they raise the inexact floatingpoint exception.
None.
feclearexcept(3p), fetestexcept(3p), llrint(3p) The Base Definitions volume of POSIX.1‐2008, Section 4.19, 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, 2013 Edition, Standard for Information
Technology  Portable 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.12008 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 Standard 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/manpages/reporting_bugs.html .
IEEE/The Open Group 2013 LRINT(3P)