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.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved 

.TH "RINT" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"

.\" rint 

.SH NAME

rint, rintf, rintl \- round-to-nearest integral value

.SH SYNOPSIS

.LP

\fB#include <math.h>

.br

.sp

double rint(double\fP \fIx\fP\fB);

.br

float rintf(float\fP \fIx\fP\fB);

.br

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

.br

\fP

.SH DESCRIPTION

.LP

These functions shall return the integral value (represented as a

\fBdouble\fP) nearest \fIx\fP in the direction of the

current rounding mode. The current rounding mode is implementation-defined.

.LP

If the current rounding mode rounds toward negative infinity, then

\fIrint\fP() shall be equivalent to \fIfloor\fP() . If the current

rounding mode rounds toward positive infinity, then \fIrint\fP() shall

be

equivalent to \fIceil\fP() .

.LP

These functions differ from the \fInearbyint\fP(), \fInearbyintf\fP(),

and \fInearbyintl\fP()

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

if the result differs in value from the argument.

.LP

An application wishing to check for error situations should set \fIerrno\fP

to zero and call

\fIfeclearexcept\fP(FE_ALL_EXCEPT) before calling these functions.

On return, if \fIerrno\fP is non-zero or

\fIfetestexcept\fP(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW)

is non-zero, an error has occurred.

.SH RETURN VALUE

.LP

Upon successful completion, these functions shall return the integer

(represented as a double precision number) nearest \fIx\fP

in the direction of the current rounding mode.

.LP

If

\fIx\fP is NaN, a NaN shall be returned.

.LP

If \fIx\fP is \(+-0 or \(+-Inf, \fIx\fP shall be returned. 

.LP

If the correct value would cause overflow, a range error shall occur

and \fIrint\fP(), \fIrintf\fP(), and \fIrintl\fP() shall

return the value of the macro \(+-HUGE_VAL, \(+-HUGE_VALF, and \(+-HUGE_VALL

(with the same sign as \fIx\fP),

respectively. 

.SH ERRORS

.LP

These functions shall fail if:

.TP 7

Range\ Error

The result would cause an overflow. 

.LP

If the integer expression (math_errhandling & MATH_ERRNO) is non-zero,

then \fIerrno\fP 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.

.sp

.LP

\fIThe following sections are informative.\fP

.SH EXAMPLES

.LP

None.

.SH APPLICATION USAGE

.LP

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.

.SH RATIONALE

.LP

None.

.SH FUTURE DIRECTIONS

.LP

None.

.SH SEE ALSO

.LP

\fIabs\fP() , \fIceil\fP() , \fIfeclearexcept\fP() , \fIfetestexcept\fP()

, \fIfloor\fP() , \fIisnan\fP() , \fInearbyint\fP() , the

Base Definitions volume of IEEE\ Std\ 1003.1-2001, Section 4.18, Treatment

of Error Conditions for Mathematical Functions, \fI<math.h>\fP

.SH COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form

from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology

-- Portable 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 .