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.\" Copyright 2001 Andries Brouwer <aeb@cwi.nl>.
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date. The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein. The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.TH ROUND 3 2001-05-31 "" "Linux Programmer's Manual"
.SH NAME
round, roundf, roundl \- round to nearest integer, away from zero
.SH SYNOPSIS
.nf
.B #include <math.h>
.sp
.BI "double round(double " x );
.br
.BI "float roundf(float " x );
.br
.BI "long double roundl(long double " x );
.fi
.sp
Compile with \-std=c99; link with \-lm.
.SH DESCRIPTION
These functions round \fIx\fP to the nearest integer, but
round halfway cases away from zero (regardless of the current rounding
direction), instead of to the nearest even integer like
.BR rint ().
.SH "RETURN VALUE"
The rounded integer value.
If \fIx\fP is integral or infinite,
\fIx\fP itself is returned.
.SH ERRORS
No errors other than EDOM and ERANGE can occur.
If \fIx\fP is NaN, then NaN is returned and
.I errno
may be set to EDOM.
.SH NOTES
POSIX.1-2001 contains text about overflow (which might set
.I errno
to ERANGE, or raise an exception).
In practice, the result cannot overflow on any current machine,
so this error-handling stuff is just nonsense.
(More precisely, overflow can happen only when the maximum value
of the exponent is smaller than the number of mantissa bits.
For the IEEE-754 standard 32-bit and 64-bit floating point numbers
the maximum value of the exponent is 128 (resp. 1024), and the number
of mantissa bits is 24 (resp. 53).)
.SH "CONFORMING TO"
C99.
.SH "SEE ALSO"
.BR ceil (3),
.BR floor (3),
.BR lround (3),
.BR nearbyint (3),
.BR rint (3),
.BR trunc (3)
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