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.TH RINT "3P" 2013 "IEEE/The Open Group" "POSIX Programmer's Manual"

.SH 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.

.SH NAME

rint,

rintf,

rintl

\(em round-to-nearest integral value

.SH SYNOPSIS

.LP

.nf

#include <math.h>

.P

double rint(double \fIx\fP);

float rintf(float \fIx\fP);

long double rintl(long double \fIx\fP);

.fi

.SH 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\(hy2008 defers to the ISO\ C standard.

.P

These functions shall return the integral value (represented as a

.BR double )

nearest

.IR x

in the direction of the current rounding mode. The current rounding

mode is implementation-defined.

.P

If the current rounding mode rounds toward negative infinity, then

\fIrint\fR()

shall be equivalent to

.IR "\fIfloor\fR\^(\|)".

If the current rounding mode rounds toward positive infinity, then

\fIrint\fR()

shall be equivalent to

.IR "\fIceil\fR\^(\|)".

If the current rounding mode rounds towards zero, then

\fIrint\fR()

shall be equivalent to

.IR "\fItrunc\fR\^(\|)".

If the current rounding mode rounds towards nearest, then

\fIrint\fR()

differs from

.IR "\fIround\fR\^(\|)"

in that halfway cases are rounded to even rather than away from zero.

.P

These functions differ from the

\fInearbyint\fR(),

\fInearbyintf\fR(),

and

\fInearbyintl\fR()

functions only in that they may raise the inexact floating-point

exception if the result differs in value from the argument.

.P

An application wishing to check for error situations should set

.IR errno

to zero and call

.IR feclearexcept (FE_ALL_EXCEPT)

before calling these functions. On return, if

.IR errno

is non-zero or \fIfetestexcept\fR(FE_INVALID | FE_DIVBYZERO |

FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.

.SH "RETURN VALUE"

Upon successful completion, these functions shall return the integer

(represented as a double precision number) nearest

.IR x

in the direction of the current rounding mode.

The result shall have the same sign as

.IR x .

.P

If

.IR x

is NaN, a NaN shall be returned.

.P

If

.IR x

is \(+-0 or \(+-Inf,

.IR x

shall be returned.

.SH ERRORS

No errors are defined.

.LP

.IR "The following sections are informative."

.SH EXAMPLES

None.

.SH "APPLICATION USAGE"

The integral value returned by these functions need not be expressible

as an

.BR intmax_t .

The return value should be tested before assigning it to an integer type

to avoid the undefined results of an integer overflow.

.SH RATIONALE

None.

.SH "FUTURE DIRECTIONS"

None.

.SH "SEE ALSO"

.IR "\fIabs\fR\^(\|)",

.IR "\fIceil\fR\^(\|)",

.IR "\fIfeclearexcept\fR\^(\|)",

.IR "\fIfetestexcept\fR\^(\|)",

.IR "\fIfloor\fR\^(\|)",

.IR "\fIisnan\fR\^(\|)",

.IR "\fInearbyint\fR\^(\|)"

.P

The Base Definitions volume of POSIX.1\(hy2008,

.IR "Section 4.19" ", " "Treatment of Error Conditions for Mathematical Functions",

.IR "\fB<math.h>\fP"

.SH COPYRIGHT

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.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 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/man-pages/reporting_bugs.html .