| .\" Copyright 2001 Andries Brouwer <aeb@cwi.nl>. |
| .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk |
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| .\" |
| .TH LROUND 3 2021-03-22 "" "Linux Programmer's Manual" |
| .SH NAME |
| lround, lroundf, lroundl, llround, llroundf, llroundl \- round to |
| nearest integer |
| .SH SYNOPSIS |
| .nf |
| .B #include <math.h> |
| .PP |
| .BI "long lround(double " x ); |
| .BI "long lroundf(float " x ); |
| .BI "long lroundl(long double " x ); |
| .PP |
| .BI "long long llround(double " x ); |
| .BI "long long llroundf(float " x ); |
| .BI "long long llroundl(long double " x ); |
| .fi |
| .PP |
| Link with \fI\-lm\fP. |
| .PP |
| .RS -4 |
| Feature Test Macro Requirements for glibc (see |
| .BR feature_test_macros (7)): |
| .RE |
| .PP |
| All functions shown above: |
| .nf |
| _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L |
| .fi |
| .SH DESCRIPTION |
| These functions round their argument to the nearest integer value, |
| rounding halfway cases away from zero, |
| regardless of the current rounding direction (see |
| .BR fenv (3)). |
| .PP |
| Note that unlike the |
| .BR round (3) |
| and |
| .BR ceil (3), |
| functions, the return type of these functions differs from |
| that of their arguments. |
| .SH RETURN VALUE |
| These functions return the rounded integer value. |
| .PP |
| If |
| .I x |
| is a NaN or an infinity, |
| or the rounded value is too large to be stored in a |
| .I long |
| .RI ( "long long" |
| in the case of the |
| .B ll* |
| functions), |
| then a domain error occurs, and the return value is unspecified. |
| .\" The return value is -(LONG_MAX - 1) or -(LLONG_MAX -1) |
| .SH ERRORS |
| See |
| .BR math_error (7) |
| for information on how to determine whether an error has occurred |
| when calling these functions. |
| .PP |
| The following errors can occur: |
| .TP |
| Domain error: \fIx\fP is a NaN or infinite, or the rounded value is too large |
| .\" .I errno |
| .\" is set to |
| .\" .BR EDOM . |
| An invalid floating-point exception |
| .RB ( FE_INVALID ) |
| is raised. |
| .PP |
| These functions do not set |
| .IR errno . |
| .\" FIXME . Is it intentional that these functions do not set errno? |
| .\" Bug raised: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6797 |
| .SH VERSIONS |
| These functions first appeared in glibc in version 2.1. |
| .SH ATTRIBUTES |
| For an explanation of the terms used in this section, see |
| .BR attributes (7). |
| .ad l |
| .nh |
| .TS |
| allbox; |
| lbx lb lb |
| l l l. |
| Interface Attribute Value |
| T{ |
| .BR lround (), |
| .BR lroundf (), |
| .BR lroundl (), |
| .BR llround (), |
| .BR llroundf (), |
| .BR llroundl () |
| T} Thread safety MT-Safe |
| .TE |
| .hy |
| .ad |
| .sp 1 |
| .SH CONFORMING TO |
| C99, POSIX.1-2001, POSIX.1-2008. |
| .SH SEE ALSO |
| .BR ceil (3), |
| .BR floor (3), |
| .BR lrint (3), |
| .BR nearbyint (3), |
| .BR rint (3), |
| .BR round (3) |