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<title>SuperLU: SRC/ilu_spivotL.c File Reference</title>
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<h1>SRC/ilu_spivotL.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__sdefs_8h-source.html">slu_sdefs.h</a>"</code><br>
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<tr><td colspan="2"><br><h2>Defines</h2></td></tr>
<tr><td class="memItemLeft" nowrap align="right" valign="top">#define </td><td class="memItemRight" valign="bottom"><a class="el" href="ilu__spivotL_8c.html#95ed41486ca0ed53262e4b8934d4afac">SGN</a>(x) ((x)>=0?1:-1)</td></tr>
<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="ilu__spivotL_8c.html#9da652b68b6ecee45919cf56f256b7e0">ilu_spivotL</a> (const int jcol, const double u, int *usepr, int *perm_r, int diagind, int *swap, int *iswap, int *marker, int *pivrow, double fill_tol, <a class="el" href="superlu__enum__consts_8h.html#0cb73c13a7c2390c3a9a0a8913477ff0">milu_t</a> milu, float drop_sum, <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 4.0) --
Lawrence Berkeley National Laboratory
June 30, 2009
</pre> <hr><h2>Define Documentation</h2>
<a class="anchor" name="95ed41486ca0ed53262e4b8934d4afac"></a><!-- doxytag: member="ilu_spivotL.c::SGN" ref="95ed41486ca0ed53262e4b8934d4afac" args="(x)" -->
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<td class="memname">#define SGN </td>
<td>(</td>
<td class="paramtype">x </td>
<td class="paramname"> </td>
<td> ) </td>
<td width="100%"> ((x)>=0?1:-1)</td>
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<hr><h2>Function Documentation</h2>
<a class="anchor" name="9da652b68b6ecee45919cf56f256b7e0"></a><!-- doxytag: member="ilu_spivotL.c::ilu_spivotL" ref="9da652b68b6ecee45919cf56f256b7e0" args="(const int jcol, const double u, int *usepr, int *perm_r, int diagind, int *swap, int *iswap, int *marker, int *pivrow, double fill_tol, milu_t milu, float drop_sum, GlobalLU_t *Glu, SuperLUStat_t *stat)" -->
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<td class="memname">int ilu_spivotL </td>
<td>(</td>
<td class="paramtype">const int </td>
<td class="paramname"> <em>jcol</em>, </td>
</tr>
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<td class="paramkey"></td>
<td></td>
<td class="paramtype">const double </td>
<td class="paramname"> <em>u</em>, </td>
</tr>
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<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>
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<td class="paramkey"></td>
<td></td>
<td class="paramtype">int </td>
<td class="paramname"> <em>diagind</em>, </td>
</tr>
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<td class="paramkey"></td>
<td></td>
<td class="paramtype">int * </td>
<td class="paramname"> <em>swap</em>, </td>
</tr>
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<td class="paramkey"></td>
<td></td>
<td class="paramtype">int * </td>
<td class="paramname"> <em>iswap</em>, </td>
</tr>
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<td class="paramkey"></td>
<td></td>
<td class="paramtype">int * </td>
<td class="paramname"> <em>marker</em>, </td>
</tr>
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<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">double </td>
<td class="paramname"> <em>fill_tol</em>, </td>
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<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="superlu__enum__consts_8h.html#0cb73c13a7c2390c3a9a0a8913477ff0">milu_t</a> </td>
<td class="paramname"> <em>milu</em>, </td>
</tr>
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<td class="paramkey"></td>
<td></td>
<td class="paramtype">float </td>
<td class="paramname"> <em>drop_sum</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>
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<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>
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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.
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