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<div class="title">SparseLU_pivotL.h</div> </div>
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<div class="fragment"><div class="line"><a name="l00001"></a><span class="lineno"> 1</span> <span class="comment">// This file is part of Eigen, a lightweight C++ template library</span></div>
<div class="line"><a name="l00002"></a><span class="lineno"> 2</span> <span class="comment">// for linear algebra.</span></div>
<div class="line"><a name="l00003"></a><span class="lineno"> 3</span> <span class="comment">//</span></div>
<div class="line"><a name="l00004"></a><span class="lineno"> 4</span> <span class="comment">// Copyright (C) 2012 Désiré Nuentsa-Wakam <desire.nuentsa_wakam@inria.fr></span></div>
<div class="line"><a name="l00005"></a><span class="lineno"> 5</span> <span class="comment">//</span></div>
<div class="line"><a name="l00006"></a><span class="lineno"> 6</span> <span class="comment">// This Source Code Form is subject to the terms of the Mozilla</span></div>
<div class="line"><a name="l00007"></a><span class="lineno"> 7</span> <span class="comment">// Public License v. 2.0. If a copy of the MPL was not distributed</span></div>
<div class="line"><a name="l00008"></a><span class="lineno"> 8</span> <span class="comment">// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.</span></div>
<div class="line"><a name="l00009"></a><span class="lineno"> 9</span> </div>
<div class="line"><a name="l00010"></a><span class="lineno"> 10</span> <span class="comment">/* </span></div>
<div class="line"><a name="l00011"></a><span class="lineno"> 11</span> <span class="comment"> </span></div>
<div class="line"><a name="l00012"></a><span class="lineno"> 12</span> <span class="comment"> * NOTE: This file is the modified version of xpivotL.c file in SuperLU </span></div>
<div class="line"><a name="l00013"></a><span class="lineno"> 13</span> <span class="comment"> </span></div>
<div class="line"><a name="l00014"></a><span class="lineno"> 14</span> <span class="comment"> * -- SuperLU routine (version 3.0) --</span></div>
<div class="line"><a name="l00015"></a><span class="lineno"> 15</span> <span class="comment"> * Univ. of California Berkeley, Xerox Palo Alto Research Center,</span></div>
<div class="line"><a name="l00016"></a><span class="lineno"> 16</span> <span class="comment"> * and Lawrence Berkeley National Lab.</span></div>
<div class="line"><a name="l00017"></a><span class="lineno"> 17</span> <span class="comment"> * October 15, 2003</span></div>
<div class="line"><a name="l00018"></a><span class="lineno"> 18</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00019"></a><span class="lineno"> 19</span> <span class="comment"> * Copyright (c) 1994 by Xerox Corporation. All rights reserved.</span></div>
<div class="line"><a name="l00020"></a><span class="lineno"> 20</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00021"></a><span class="lineno"> 21</span> <span class="comment"> * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY</span></div>
<div class="line"><a name="l00022"></a><span class="lineno"> 22</span> <span class="comment"> * EXPRESSED OR IMPLIED. ANY USE IS AT YOUR OWN RISK.</span></div>
<div class="line"><a name="l00023"></a><span class="lineno"> 23</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00024"></a><span class="lineno"> 24</span> <span class="comment"> * Permission is hereby granted to use or copy this program for any</span></div>
<div class="line"><a name="l00025"></a><span class="lineno"> 25</span> <span class="comment"> * purpose, provided the above notices are retained on all copies.</span></div>
<div class="line"><a name="l00026"></a><span class="lineno"> 26</span> <span class="comment"> * Permission to modify the code and to distribute modified code is</span></div>
<div class="line"><a name="l00027"></a><span class="lineno"> 27</span> <span class="comment"> * granted, provided the above notices are retained, and a notice that</span></div>
<div class="line"><a name="l00028"></a><span class="lineno"> 28</span> <span class="comment"> * the code was modified is included with the above copyright notice.</span></div>
<div class="line"><a name="l00029"></a><span class="lineno"> 29</span> <span class="comment"> */</span></div>
<div class="line"><a name="l00030"></a><span class="lineno"> 30</span> <span class="preprocessor">#ifndef SPARSELU_PIVOTL_H</span></div>
<div class="line"><a name="l00031"></a><span class="lineno"> 31</span> <span class="preprocessor"></span><span class="preprocessor">#define SPARSELU_PIVOTL_H</span></div>
<div class="line"><a name="l00032"></a><span class="lineno"> 32</span> <span class="preprocessor"></span></div>
<div class="line"><a name="l00033"></a><span class="lineno"> 33</span> <span class="keyword">namespace </span>Eigen {</div>
<div class="line"><a name="l00034"></a><span class="lineno"> 34</span> <span class="keyword">namespace </span>internal {</div>
<div class="line"><a name="l00035"></a><span class="lineno"> 35</span>  </div>
<div class="line"><a name="l00059"></a><span class="lineno"> 59</span> <span class="keyword">template</span> <<span class="keyword">typename</span> Scalar, <span class="keyword">typename</span> Index></div>
<div class="line"><a name="l00060"></a><span class="lineno"> 60</span> Index SparseLUImpl<Scalar,Index>::pivotL(<span class="keyword">const</span> Index jcol, <span class="keyword">const</span> RealScalar& diagpivotthresh, IndexVector& perm_r, IndexVector& iperm_c, Index& pivrow, GlobalLU_t& glu)</div>
<div class="line"><a name="l00061"></a><span class="lineno"> 61</span> {</div>
<div class="line"><a name="l00062"></a><span class="lineno"> 62</span>  </div>
<div class="line"><a name="l00063"></a><span class="lineno"> 63</span>  Index fsupc = (glu.xsup)((glu.supno)(jcol)); <span class="comment">// First column in the supernode containing the column jcol</span></div>
<div class="line"><a name="l00064"></a><span class="lineno"> 64</span>  Index nsupc = jcol - fsupc; <span class="comment">// Number of columns in the supernode portion, excluding jcol; nsupc >=0</span></div>
<div class="line"><a name="l00065"></a><span class="lineno"> 65</span>  Index lptr = glu.xlsub(fsupc); <span class="comment">// pointer to the starting location of the row subscripts for this supernode portion</span></div>
<div class="line"><a name="l00066"></a><span class="lineno"> 66</span>  Index nsupr = glu.xlsub(fsupc+1) - lptr; <span class="comment">// Number of rows in the supernode</span></div>
<div class="line"><a name="l00067"></a><span class="lineno"> 67</span>  Index lda = glu.xlusup(fsupc+1) - glu.xlusup(fsupc); <span class="comment">// leading dimension</span></div>
<div class="line"><a name="l00068"></a><span class="lineno"> 68</span>  Scalar* lu_sup_ptr = &(glu.lusup.data()[glu.xlusup(fsupc)]); <span class="comment">// Start of the current supernode</span></div>
<div class="line"><a name="l00069"></a><span class="lineno"> 69</span>  Scalar* lu_col_ptr = &(glu.lusup.data()[glu.xlusup(jcol)]); <span class="comment">// Start of jcol in the supernode</span></div>
<div class="line"><a name="l00070"></a><span class="lineno"> 70</span>  Index* lsub_ptr = &(glu.lsub.data()[lptr]); <span class="comment">// Start of row indices of the supernode</span></div>
<div class="line"><a name="l00071"></a><span class="lineno"> 71</span>  </div>
<div class="line"><a name="l00072"></a><span class="lineno"> 72</span>  <span class="comment">// Determine the largest abs numerical value for partial pivoting </span></div>
<div class="line"><a name="l00073"></a><span class="lineno"> 73</span>  Index diagind = iperm_c(jcol); <span class="comment">// diagonal index </span></div>
<div class="line"><a name="l00074"></a><span class="lineno"> 74</span>  RealScalar pivmax = 0.0; </div>
<div class="line"><a name="l00075"></a><span class="lineno"> 75</span>  Index pivptr = nsupc; </div>
<div class="line"><a name="l00076"></a><span class="lineno"> 76</span>  Index diag = emptyIdxLU; </div>
<div class="line"><a name="l00077"></a><span class="lineno"> 77</span>  RealScalar rtemp;</div>
<div class="line"><a name="l00078"></a><span class="lineno"> 78</span>  Index isub, icol, itemp, k; </div>
<div class="line"><a name="l00079"></a><span class="lineno"> 79</span>  <span class="keywordflow">for</span> (isub = nsupc; isub < nsupr; ++isub) {</div>
<div class="line"><a name="l00080"></a><span class="lineno"> 80</span>  rtemp = std::abs(lu_col_ptr[isub]);</div>
<div class="line"><a name="l00081"></a><span class="lineno"> 81</span>  <span class="keywordflow">if</span> (rtemp > pivmax) {</div>
<div class="line"><a name="l00082"></a><span class="lineno"> 82</span>  pivmax = rtemp; </div>
<div class="line"><a name="l00083"></a><span class="lineno"> 83</span>  pivptr = isub;</div>
<div class="line"><a name="l00084"></a><span class="lineno"> 84</span>  } </div>
<div class="line"><a name="l00085"></a><span class="lineno"> 85</span>  <span class="keywordflow">if</span> (lsub_ptr[isub] == diagind) diag = isub;</div>
<div class="line"><a name="l00086"></a><span class="lineno"> 86</span>  }</div>
<div class="line"><a name="l00087"></a><span class="lineno"> 87</span>  </div>
<div class="line"><a name="l00088"></a><span class="lineno"> 88</span>  <span class="comment">// Test for singularity</span></div>
<div class="line"><a name="l00089"></a><span class="lineno"> 89</span>  <span class="keywordflow">if</span> ( pivmax == 0.0 ) {</div>
<div class="line"><a name="l00090"></a><span class="lineno"> 90</span>  pivrow = lsub_ptr[pivptr];</div>
<div class="line"><a name="l00091"></a><span class="lineno"> 91</span>  perm_r(pivrow) = jcol;</div>
<div class="line"><a name="l00092"></a><span class="lineno"> 92</span>  <span class="keywordflow">return</span> (jcol+1);</div>
<div class="line"><a name="l00093"></a><span class="lineno"> 93</span>  }</div>
<div class="line"><a name="l00094"></a><span class="lineno"> 94</span>  </div>
<div class="line"><a name="l00095"></a><span class="lineno"> 95</span>  RealScalar thresh = diagpivotthresh * pivmax; </div>
<div class="line"><a name="l00096"></a><span class="lineno"> 96</span>  </div>
<div class="line"><a name="l00097"></a><span class="lineno"> 97</span>  <span class="comment">// Choose appropriate pivotal element </span></div>
<div class="line"><a name="l00098"></a><span class="lineno"> 98</span>  </div>
<div class="line"><a name="l00099"></a><span class="lineno"> 99</span>  {</div>
<div class="line"><a name="l00100"></a><span class="lineno"> 100</span>  <span class="comment">// Test if the diagonal element can be used as a pivot (given the threshold value)</span></div>
<div class="line"><a name="l00101"></a><span class="lineno"> 101</span>  <span class="keywordflow">if</span> (diag >= 0 ) </div>
<div class="line"><a name="l00102"></a><span class="lineno"> 102</span>  {</div>
<div class="line"><a name="l00103"></a><span class="lineno"> 103</span>  <span class="comment">// Diagonal element exists</span></div>
<div class="line"><a name="l00104"></a><span class="lineno"> 104</span>  rtemp = std::abs(lu_col_ptr[diag]);</div>
<div class="line"><a name="l00105"></a><span class="lineno"> 105</span>  <span class="keywordflow">if</span> (rtemp != 0.0 && rtemp >= thresh) pivptr = diag;</div>
<div class="line"><a name="l00106"></a><span class="lineno"> 106</span>  }</div>
<div class="line"><a name="l00107"></a><span class="lineno"> 107</span>  pivrow = lsub_ptr[pivptr];</div>
<div class="line"><a name="l00108"></a><span class="lineno"> 108</span>  }</div>
<div class="line"><a name="l00109"></a><span class="lineno"> 109</span>  </div>
<div class="line"><a name="l00110"></a><span class="lineno"> 110</span>  <span class="comment">// Record pivot row</span></div>
<div class="line"><a name="l00111"></a><span class="lineno"> 111</span>  perm_r(pivrow) = jcol; </div>
<div class="line"><a name="l00112"></a><span class="lineno"> 112</span>  <span class="comment">// Interchange row subscripts</span></div>
<div class="line"><a name="l00113"></a><span class="lineno"> 113</span>  <span class="keywordflow">if</span> (pivptr != nsupc )</div>
<div class="line"><a name="l00114"></a><span class="lineno"> 114</span>  {</div>
<div class="line"><a name="l00115"></a><span class="lineno"> 115</span>  std::swap( lsub_ptr[pivptr], lsub_ptr[nsupc] );</div>
<div class="line"><a name="l00116"></a><span class="lineno"> 116</span>  <span class="comment">// Interchange numerical values as well, for the two rows in the whole snode</span></div>
<div class="line"><a name="l00117"></a><span class="lineno"> 117</span>  <span class="comment">// such that L is indexed the same way as A</span></div>
<div class="line"><a name="l00118"></a><span class="lineno"> 118</span>  <span class="keywordflow">for</span> (icol = 0; icol <= nsupc; icol++)</div>
<div class="line"><a name="l00119"></a><span class="lineno"> 119</span>  {</div>
<div class="line"><a name="l00120"></a><span class="lineno"> 120</span>  itemp = pivptr + icol * lda; </div>
<div class="line"><a name="l00121"></a><span class="lineno"> 121</span>  std::swap(lu_sup_ptr[itemp], lu_sup_ptr[nsupc + icol * lda]);</div>
<div class="line"><a name="l00122"></a><span class="lineno"> 122</span>  }</div>
<div class="line"><a name="l00123"></a><span class="lineno"> 123</span>  }</div>
<div class="line"><a name="l00124"></a><span class="lineno"> 124</span>  <span class="comment">// cdiv operations</span></div>
<div class="line"><a name="l00125"></a><span class="lineno"> 125</span>  Scalar temp = Scalar(1.0) / lu_col_ptr[nsupc];</div>
<div class="line"><a name="l00126"></a><span class="lineno"> 126</span>  <span class="keywordflow">for</span> (k = nsupc+1; k < nsupr; k++)</div>
<div class="line"><a name="l00127"></a><span class="lineno"> 127</span>  lu_col_ptr[k] *= temp; </div>
<div class="line"><a name="l00128"></a><span class="lineno"> 128</span>  <span class="keywordflow">return</span> 0;</div>
<div class="line"><a name="l00129"></a><span class="lineno"> 129</span> }</div>
<div class="line"><a name="l00130"></a><span class="lineno"> 130</span> </div>
<div class="line"><a name="l00131"></a><span class="lineno"> 131</span> } <span class="comment">// end namespace internal</span></div>
<div class="line"><a name="l00132"></a><span class="lineno"> 132</span> } <span class="comment">// end namespace Eigen</span></div>
<div class="line"><a name="l00133"></a><span class="lineno"> 133</span> </div>
<div class="line"><a name="l00134"></a><span class="lineno"> 134</span> <span class="preprocessor">#endif // SPARSELU_PIVOTL_H</span></div>
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