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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta name="generator" content="HTML Tidy, see www.w3.org"><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 --><!-- Copyright (c) 2001-2004 IEEE and The Open Group, All Rights Reserved --><title>y0</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <a name="y0"></a> <a name="tag_03_869"></a><!-- y0 --> <!--header start--><center><font size="2">The Open Group Base Specifications Issue 6<br>IEEE Std 1003.1, 2004 Edition<br>Copyright © 2001-2004 The IEEE and The Open Group, All Rights reserved.</font></center><!--header end--><hr size="2" noshade><h4><a name="tag_03_869_01"></a>NAME</h4><blockquote>y0, y1, yn - Bessel functions of the second kind</blockquote><h4><a name="tag_03_869_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><div class="box"><code><tt><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> #include <<a href="../basedefs/math.h.html">math.h</a>><br><br> double y0(double</tt> <i>x</i><tt>);<br> double y1(double</tt> <i>x</i><tt>);<br> double yn(int</tt> <i>n</i><tt>, double</tt> <i>x</i><tt>); <img src="../images/opt-end.gif" alt="[Option End]" border="0"></tt></code></div><tt><br></tt></blockquote><h4><a name="tag_03_869_03"></a>DESCRIPTION</h4><blockquote><p>The <i>y0</i>(), <i>y1</i>(), and <i>yn</i>() functions shall compute Bessel functions of <i>x</i> of the second kind of orders0, 1, and <i>n</i>, respectively.</p><p>An application wishing to check for error situations should set <i>errno</i> to zero and call<i>feclearexcept</i>(FE_ALL_EXCEPT) before calling these functions. On return, if <i>errno</i> is non-zero or<i>fetestexcept</i>(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.</p></blockquote><h4><a name="tag_03_869_04"></a>RETURN VALUE</h4><blockquote><p>Upon successful completion, these functions shall return the relevant Bessel value of <i>x</i> of the second kind.</p><p>If <i>x</i> is NaN, NaN shall be returned.</p><p>If the <i>x</i> argument to these functions is negative, -HUGE_VAL or NaN shall be returned, and a domain error may occur.</p><p>If <i>x</i> is 0.0, -HUGE_VAL shall be returned and a pole error may occur.</p><p>If the correct result would cause underflow, 0.0 shall be returned and a range error may occur.</p><p>If the correct result would cause overflow, -HUGE_VAL or 0.0 shall be returned and a range error may occur.</p></blockquote><h4><a name="tag_03_869_05"></a>ERRORS</h4><blockquote><p>These functions may fail if:</p><dl compact><dt>Domain Error</dt><dd>The value of <i>x</i> is negative. <p>If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then <i>errno</i> shall be set to [EDOM]. If theinteger expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the invalid floating-point exception shall beraised.</p></dd><dt>Pole Error</dt><dd>The value of <i>x</i> is zero. <p>If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then <i>errno</i> shall be set to [ERANGE]. If theinteger expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the divide-by-zero floating-point exception shall beraised.</p></dd><dt>Range Error</dt><dd>The correct result would cause overflow. <p>If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then <i>errno</i> shall be set to [ERANGE]. If theinteger expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the overflow floating-point exception shall beraised.</p></dd><dt>Range Error</dt><dd>The value of <i>x</i> is too large in magnitude, or the correct result would cause underflow. <p>If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then <i>errno</i> shall be set to [ERANGE]. If theinteger expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the underflow floating-point exception shall beraised.</p></dd></dl></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_03_869_06"></a>EXAMPLES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_869_07"></a>APPLICATION USAGE</h4><blockquote><p>On error, the expressions (math_errhandling & MATH_ERRNO) and (math_errhandling & MATH_ERREXCEPT) are independent ofeach other, but at least one of them must be non-zero.</p></blockquote><h4><a name="tag_03_869_08"></a>RATIONALE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_869_09"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_869_10"></a>SEE ALSO</h4><blockquote><p><a href="feclearexcept.html"><i>feclearexcept</i>()</a>, <a href="fetestexcept.html"><i>fetestexcept</i>()</a>, <a href="isnan.html"><i>isnan</i>()</a>, <a href="j0.html"><i>j0</i>()</a>, the Base Definitions volume ofIEEE Std 1003.1-2001, <a href="../basedefs/xbd_chap04.html#tag_04_18">Section 4.18, Treatment of Error Conditions forMathematical Functions</a>, <a href="../basedefs/math.h.html"><i><math.h></i></a></p></blockquote><h4><a name="tag_03_869_11"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 1. Derived from Issue 1 of the SVID.</p></blockquote><h4><a name="tag_03_869_12"></a>Issue 5</h4><blockquote><p>The DESCRIPTION is updated to indicate how an application should check for an error. This text was previously published in theAPPLICATION USAGE section.</p></blockquote><h4><a name="tag_03_869_13"></a>Issue 6</h4><blockquote><p>The DESCRIPTION is updated to avoid use of the term "must" for application requirements.</p><p>The RETURN VALUE and ERRORS sections are reworked for alignment of the error handling with the ISO/IEC 9899:1999standard.</p><p>IEEE Std 1003.1-2001/Cor 2-2004, item XSH/TC2/D6/148 is applied, updating the RETURN VALUE and ERRORS sections.The changes are made for consistency with the general rules stated in "Treatment of Error Conditions for Mathematical Functions''in the Base Definitions volume of IEEE Std 1003.1-2001.</p></blockquote><div class="box"><em>End of informative text.</em></div><hr size="2" noshade><center><font size="2"><!--footer start-->UNIX ® is a registered Trademark of The Open Group.<br>POSIX ® is a registered Trademark of The IEEE.<br>[ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href="../utilities/contents.html">XCU</a> | <a href="../functions/contents.html">XSH</a> | <a href="../xrat/contents.html">XRAT</a>]</font></center><!--footer end--><hr size="2" noshade></body></html>⌨️ 快捷键说明
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