151 lines
6.1 KiB
HTML
151 lines
6.1 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 -->
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<!-- Copyright (c) 2001 The Open Group, All Rights Reserved -->
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<title>lround</title>
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<body bgcolor="white">
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<script type="text/javascript" language="JavaScript" src="../jscript/codes.js">
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<basefont size="3"> <a name="lround"></a> <a name="tag_03_352"></a><!-- lround -->
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<!--header start-->
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<center><font size="2">The Open Group Base Specifications Issue 6<br>
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IEEE Std 1003.1-2001<br>
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Copyright © 2001 The IEEE and The Open Group, All Rights reserved.</font></center>
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<!--header end-->
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<hr size="2" noshade>
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<h4><a name="tag_03_352_01"></a>NAME</h4>
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<blockquote>lround, lroundf, lroundl - round to nearest integer value</blockquote>
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<h4><a name="tag_03_352_02"></a>SYNOPSIS</h4>
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<blockquote class="synopsis">
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<p><code><tt>#include <<a href="../basedefs/math.h.html">math.h</a>><br>
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<br>
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long lround(double</tt> <i>x</i><tt>);<br>
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long lroundf(float</tt> <i>x</i><tt>);<br>
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long lroundl(long double</tt> <i>x</i><tt>);<br>
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</tt></code></p>
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</blockquote>
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<h4><a name="tag_03_352_03"></a>DESCRIPTION</h4>
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<blockquote>
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<div class="box"><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]"
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border="0"> The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the
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requirements described here and the ISO C standard is unintentional. This volume of IEEE Std 1003.1-2001 defers to
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the ISO C standard. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></div>
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<p>These functions shall round their argument to the nearest integer value, rounding halfway cases away from zero, regardless of
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the current rounding direction.</p>
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<p>An application wishing to check for error situations should set <i>errno</i> to zero and call
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<i>feclearexcept</i>(FE_ALL_EXCEPT) before calling these functions. On return, if <i>errno</i> is non-zero or
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<i>fetestexcept</i>(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.</p>
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</blockquote>
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<h4><a name="tag_03_352_04"></a>RETURN VALUE</h4>
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<blockquote>
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<p>Upon successful completion, these functions shall return the rounded integer value.</p>
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<p><sup>[<a href="javascript:open_code('MX')">MX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> If
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<i>x</i> is NaN, a domain error shall occur and an unspecified value is returned.</p>
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<p>If <i>x</i> is +Inf, a domain error shall occur and an unspecified value is returned.</p>
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<p>If <i>x</i> is -Inf, a domain error shall occur and an unspecified value is returned.</p>
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<p>If the correct value is positive and too large to represent as a <b>long</b>, a domain error shall occur and an unspecified
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value is returned.</p>
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<p>If the correct value is negative and too large to represent as a <b>long</b>, a domain error shall occur and an unspecified
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value is returned. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></p>
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</blockquote>
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<h4><a name="tag_03_352_05"></a>ERRORS</h4>
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<blockquote>
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<p>These functions shall fail if:</p>
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<dl compact>
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<dt>Domain Error</dt>
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<dd><sup>[<a href="javascript:open_code('MX')">MX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
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The <i>x</i> argument is NaN or ±Inf, or the correct value is not representable as an integer.
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<p>If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then <i>errno</i> shall be set to [EDOM]. If the
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integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the invalid floating-point exception shall be raised.
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<img src="../images/opt-end.gif" alt="[Option End]" border="0"></p>
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</dd>
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</dl>
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</blockquote>
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<hr>
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<div class="box"><em>The following sections are informative.</em></div>
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<h4><a name="tag_03_352_06"></a>EXAMPLES</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_352_07"></a>APPLICATION USAGE</h4>
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<blockquote>
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<p>On error, the expressions (math_errhandling & MATH_ERRNO) and (math_errhandling & MATH_ERREXCEPT) are independent of
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each other, but at least one of them must be non-zero.</p>
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</blockquote>
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<h4><a name="tag_03_352_08"></a>RATIONALE</h4>
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<blockquote>
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<p>These functions differ from the <a href="../functions/lrint.html"><i>lrint</i>()</a> functions in the default rounding
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direction, with the <i>lround</i>() functions rounding halfway cases away from zero and needing not to raise the inexact
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floating-point exception for non-integer arguments that round to within the range of the return type.</p>
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</blockquote>
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<h4><a name="tag_03_352_09"></a>FUTURE DIRECTIONS</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_352_10"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="feclearexcept.html"><i>feclearexcept</i>()</a> , <a href="fetestexcept.html"><i>fetestexcept</i>()</a> , <a href=
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"llround.html"><i>llround</i>()</a> , the Base Definitions volume of IEEE Std 1003.1-2001, <a href=
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"../basedefs/xbd_chap04.html#tag_04_18">Section 4.18, Treatment of Error Conditions for Mathematical Functions</a>, <a href=
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"../basedefs/math.h.html"><i><math.h></i></a></p>
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</blockquote>
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<h4><a name="tag_03_352_11"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 6. Derived from the ISO/IEC 9899:1999 standard.</p>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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