170 lines
6.7 KiB
HTML
170 lines
6.7 KiB
HTML
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<!-- Copyright (c) 2001 The Open Group, All Rights Reserved -->
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<title>ceil</title>
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<basefont size="3"> <a name="ceil"></a> <a name="tag_03_63"></a><!-- ceil -->
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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_63_01"></a>NAME</h4>
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<blockquote>ceil, ceilf, ceill - ceiling value function</blockquote>
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<h4><a name="tag_03_63_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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double ceil(double</tt> <i>x</i><tt>);<br>
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float ceilf(float</tt> <i>x</i><tt>);<br>
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long double ceill(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_63_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 compute the smallest integral value not less than <i>x</i>.</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_63_04"></a>RETURN VALUE</h4>
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<blockquote>
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<p>Upon successful completion, <i>ceil</i>(), <i>ceilf</i>(), and <i>ceill</i>() shall return the smallest integral value not less
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than <i>x</i>, expressed as a type <b>double</b>, <b>float</b>, or <b>long double</b>, respectively.</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 NaN shall be returned.</p>
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<p>If <i>x</i> is ±0 or ±Inf, <i>x</i> shall be returned. <img src="../images/opt-end.gif" alt="[Option End]" border=
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"0"></p>
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<p><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
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If the correct value would cause overflow, a range error shall occur and <i>ceil</i>(), <i>ceilf</i>(), and <i>ceill</i>() shall
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return the value of the macro HUGE_VAL, HUGE_VALF, and HUGE_VALL, respectively. <img src="../images/opt-end.gif" alt="[Option End]"
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border="0"></p>
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</blockquote>
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<h4><a name="tag_03_63_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>Range Error</dt>
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<dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
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The result overflows.
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<p>If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then <i>errno</i> shall be set to [ERANGE]. If the
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integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the overflow 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_63_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_63_07"></a>APPLICATION USAGE</h4>
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<blockquote>
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<p>The integral value returned by these functions need not be expressible as an <b>int</b> or <b>long</b>. The return value should
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be tested before assigning it to an integer type to avoid the undefined results of an integer overflow.</p>
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<p>The <i>ceil</i>() function can only overflow when the floating-point representation has DBL_MANT_DIG > DBL_MAX_EXP.</p>
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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_63_08"></a>RATIONALE</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_63_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_63_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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"floor.html"><i>floor</i>()</a> , <a href="isnan.html"><i>isnan</i>()</a> , the Base Definitions volume of
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IEEE Std 1003.1-2001, <a href="../basedefs/xbd_chap04.html#tag_04_18">Section 4.18, Treatment of Error Conditions for
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Mathematical Functions</a>, <a href="../basedefs/math.h.html"><i><math.h></i></a></p>
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</blockquote>
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<h4><a name="tag_03_63_11"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 1. Derived from Issue 1 of the SVID.</p>
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</blockquote>
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<h4><a name="tag_03_63_12"></a>Issue 5</h4>
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<blockquote>
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<p>The DESCRIPTION is updated to indicate how an application should check for an error. This text was previously published in the
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APPLICATION USAGE section.</p>
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</blockquote>
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<h4><a name="tag_03_63_13"></a>Issue 6</h4>
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<blockquote>
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<p>The <i>ceilf</i>() and <i>ceill</i>() functions are added for alignment with the ISO/IEC 9899:1999 standard.</p>
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<p>The DESCRIPTION, RETURN VALUE, ERRORS, and APPLICATION USAGE sections are revised to align with the ISO/IEC 9899:1999
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standard.</p>
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<p>IEC 60559:1989 standard floating-point extensions over the ISO/IEC 9899:1999 standard are marked.</p>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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