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   lrint.3p    ( 3 )

округлить до ближайшего целого значения с использованием текущего направления округления (round to nearest integer value using current rounding direction)

Пролог (Prolog)

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.

Имя (Name)

lrint, lrintf, lrintl — round to nearest integer value using
       current rounding direction

Синопсис (Synopsis)

#include <math.h>

long lrint(double x); long lrintf(float x); long lrintl(long double x);


Описание (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.1‐2017 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 non-zero or fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.


Возвращаемое значение (Return value)

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 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, 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.


Ошибки (Error)

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.


Примеры (Examples)

None.

Использование в приложениях (Application usage)

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.

Обоснование (Rationale)

These functions provide floating-to-integer 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 floating-point exception is
       raised. When they raise no other floating-point exception and the
       result differs from the argument, they raise the inexact
       floating-point exception.

Будущие направления (Future directions)

None.

Смотри также (See also)

feclearexcept(3p), fetestexcept(3p), llrint(3p)

The Base Definitions volume of POSIX.1‐2017, Section 4.20, Treatment of Error Conditions for Mathematical Functions, math.h(0p)