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<title>SuperLU: SRC/dpivotL.c File Reference</title>
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<h1>SRC/dpivotL.c File Reference</h1>Performs numerical pivoting. <a href="#_details">More...</a>
<p>
<code>#include <math.h></code><br>
<code>#include <stdlib.h></code><br>
<code>#include "<a class="el" href="slu__ddefs_8h-source.html">slu_ddefs.h</a>"</code><br>
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<tr><td colspan="2"><br><h2>Functions</h2></td></tr>
<tr><td class="memItemLeft" nowrap align="right" valign="top">int </td><td class="memItemRight" valign="bottom"><a class="el" href="dpivotL_8c.html#c9bc2a5673ddfce2452bf4a88b97a266">dpivotL</a> (const int jcol, const double u, int *usepr, int *perm_r, int *iperm_r, int *iperm_c, int *pivrow, <a class="el" href="structGlobalLU__t.html">GlobalLU_t</a> *Glu, <a class="el" href="structSuperLUStat__t.html">SuperLUStat_t</a> *stat)</td></tr>
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<hr><a name="_details"></a><h2>Detailed Description</h2>
<pre>
-- SuperLU routine (version 3.0) --
Univ. of California Berkeley, Xerox Palo Alto Research Center,
and Lawrence Berkeley National Lab.
October 15, 2003</pre><p>
<pre> Copyright (c) 1994 by Xerox Corporation. All rights reserved.</pre><p>
<pre> THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY
EXPRESSED OR IMPLIED. ANY USE IS AT YOUR OWN RISK.</pre><p>
<pre> Permission is hereby granted to use or copy this program for any
purpose, provided the above notices are retained on all copies.
Permission to modify the code and to distribute modified code is
granted, provided the above notices are retained, and a notice that
the code was modified is included with the above copyright notice.
</pre> <hr><h2>Function Documentation</h2>
<a class="anchor" name="c9bc2a5673ddfce2452bf4a88b97a266"></a><!-- doxytag: member="dpivotL.c::dpivotL" ref="c9bc2a5673ddfce2452bf4a88b97a266" args="(const int jcol, const double u, int *usepr, int *perm_r, int *iperm_r, int *iperm_c, int *pivrow, GlobalLU_t *Glu, SuperLUStat_t *stat)" -->
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<td class="memname">int dpivotL </td>
<td>(</td>
<td class="paramtype">const int </td>
<td class="paramname"> <em>jcol</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">const double </td>
<td class="paramname"> <em>u</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">int * </td>
<td class="paramname"> <em>usepr</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">int * </td>
<td class="paramname"> <em>perm_r</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">int * </td>
<td class="paramname"> <em>iperm_r</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">int * </td>
<td class="paramname"> <em>iperm_c</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">int * </td>
<td class="paramname"> <em>pivrow</em>, </td>
</tr>
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<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="structGlobalLU__t.html">GlobalLU_t</a> * </td>
<td class="paramname"> <em>Glu</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="structSuperLUStat__t.html">SuperLUStat_t</a> * </td>
<td class="paramname"> <em>stat</em></td><td> </td>
</tr>
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<td></td>
<td>)</td>
<td></td><td></td><td width="100%"></td>
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<p>
<pre>
Purpose
=======
Performs the numerical pivoting on the current column of L,
and the CDIV operation.</pre><p>
<pre> Pivot policy:
(1) Compute thresh = u * max_(i>=j) <a class="el" href="slamch_8c.html#3aa069ac3980707dae1e0530f50d59e4">abs(A_ij)</a>;
(2) IF user specifies pivot row k and <a class="el" href="slamch_8c.html#3aa069ac3980707dae1e0530f50d59e4">abs(A_kj)</a> >= thresh THEN
pivot row = k;
ELSE IF <a class="el" href="slamch_8c.html#3aa069ac3980707dae1e0530f50d59e4">abs(A_jj)</a> >= thresh THEN
pivot row = j;
ELSE
pivot row = m;</pre><p>
<pre> Note: If you absolutely want to use a given pivot order, then set u=0.0.</pre><p>
<pre> Return value: 0 success;
i > 0 U(i,i) is exactly zero.
</pre>
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