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<h1>SRC/dgsitrf.c File Reference</h1><code>#include &quot;<a class="el" href="slu__ddefs_8h-source.html">slu_ddefs.h</a>&quot;</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">void&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="dgsitrf_8c.html#ffb50badd1ff77dbe19f6df360f98e50">dgsitrf</a> (<a class="el" href="structsuperlu__options__t.html">superlu_options_t</a> *options, <a class="el" href="structSuperMatrix.html">SuperMatrix</a> *<a class="el" href="ilu__zdrop__row_8c.html#c900805a486cbb8489e3c176ed6e0d8e">A</a>, int relax, int panel_size, int *etree, void *work, int lwork, int *perm_c, int *perm_r, <a class="el" href="structSuperMatrix.html">SuperMatrix</a> *L, <a class="el" href="structSuperMatrix.html">SuperMatrix</a> *U, <a class="el" href="structSuperLUStat__t.html">SuperLUStat_t</a> *stat, int *info)</td></tr>

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<hr><h2>Function Documentation</h2>
<a class="anchor" name="ffb50badd1ff77dbe19f6df360f98e50"></a><!-- doxytag: member="dgsitrf.c::dgsitrf" ref="ffb50badd1ff77dbe19f6df360f98e50" args="(superlu_options_t *options, SuperMatrix *A, int relax, int panel_size, int *etree, void *work, int lwork, int *perm_c, int *perm_r, SuperMatrix *L, SuperMatrix *U, SuperLUStat_t *stat, int *info)" -->
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          <td class="memname">void dgsitrf           </td>
          <td>(</td>
          <td class="paramtype"><a class="el" href="structsuperlu__options__t.html">superlu_options_t</a> *&nbsp;</td>
          <td class="paramname"> <em>options</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype"><a class="el" href="structSuperMatrix.html">SuperMatrix</a> *&nbsp;</td>
          <td class="paramname"> <em>A</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">int&nbsp;</td>
          <td class="paramname"> <em>relax</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">int&nbsp;</td>
          <td class="paramname"> <em>panel_size</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">int *&nbsp;</td>
          <td class="paramname"> <em>etree</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">void *&nbsp;</td>
          <td class="paramname"> <em>work</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">int&nbsp;</td>
          <td class="paramname"> <em>lwork</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">int *&nbsp;</td>
          <td class="paramname"> <em>perm_c</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">int *&nbsp;</td>
          <td class="paramname"> <em>perm_r</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype"><a class="el" href="structSuperMatrix.html">SuperMatrix</a> *&nbsp;</td>
          <td class="paramname"> <em>L</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype"><a class="el" href="structSuperMatrix.html">SuperMatrix</a> *&nbsp;</td>
          <td class="paramname"> <em>U</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype"><a class="el" href="structSuperLUStat__t.html">SuperLUStat_t</a> *&nbsp;</td>
          <td class="paramname"> <em>stat</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype">int *&nbsp;</td>
          <td class="paramname"> <em>info</em></td><td>&nbsp;</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
 =======</pre><p>
<pre> DGSITRF computes an ILU factorization of a general sparse m-by-n
 matrix A using partial pivoting with row interchanges.
 The factorization has the form
     Pr * A = L * U
 where Pr is a row permutation matrix, L is lower triangular with unit
 diagonal elements (lower trapezoidal if A-&gt;nrow &gt; A-&gt;ncol), and U is upper
 triangular (upper trapezoidal if A-&gt;nrow &lt; A-&gt;ncol).</pre><p>
<pre> See <a class="el" href="supermatrix_8h.html" title="Defines matrix types.">supermatrix.h</a> for the definition of 'SuperMatrix' structure.</pre><p>
<pre> Arguments
 =========</pre><p>
<pre> options (input) superlu_options_t*
	   The structure defines the input parameters to control
	   how the ILU decomposition will be performed.</pre><p>
<pre> A	    (input) SuperMatrix*
	    Original matrix A, permuted by columns, of dimension
	    (A-&gt;nrow, A-&gt;ncol). The type of A can be:
	    Stype = SLU_NCP; Dtype = SLU_D; Mtype = SLU_GE.</pre><p>
<pre> relax    (input) int
	    To control degree of relaxing supernodes. If the number
	    of nodes (columns) in a subtree of the elimination tree is less
	    than relax, this subtree is considered as one supernode,
	    regardless of the row structures of those columns.</pre><p>
<pre> panel_size (input) int
	    A panel consists of at most panel_size consecutive columns.</pre><p>
<pre> etree    (input) int*, dimension (A-&gt;ncol)
	    Elimination tree of A'*A.
	    Note: etree is a vector of parent pointers for a forest whose
	    vertices are the integers 0 to A-&gt;ncol-1; etree[root]==A-&gt;ncol.
	    On input, the columns of A should be permuted so that the
	    etree is in a certain postorder.</pre><p>
<pre> work     (input/output) void*, size (lwork) (in bytes)
	    User-supplied work space and space for the output data structures.
	    Not referenced if lwork = 0;</pre><p>
<pre> lwork   (input) int
	   Specifies the size of work array in bytes.
	   = 0:  allocate space internally by system malloc;
	   &gt; 0:  use user-supplied work array of length lwork in bytes,
		 returns error if space runs out.
	   = -1: the routine guesses the amount of space needed without
		 performing the factorization, and returns it in
		 *info; no other side effects.</pre><p>
<pre> perm_c   (input) int*, dimension (A-&gt;ncol)
	    Column permutation vector, which defines the
	    permutation matrix Pc; perm_c[i] = j means column i of A is
	    in position j in A*Pc.
	    When searching for diagonal, perm_c[*] is applied to the
	    row subscripts of A, so that diagonal threshold pivoting
	    can find the diagonal of A, rather than that of A*Pc.</pre><p>
<pre> perm_r   (input/output) int*, dimension (A-&gt;nrow)
	    Row permutation vector which defines the permutation matrix Pr,
	    perm_r[i] = j means row i of A is in position j in Pr*A.
	    If options-&gt;Fact = SamePattern_SameRowPerm, the pivoting routine
	       will try to use the input perm_r, unless a certain threshold
	       criterion is violated. In that case, perm_r is overwritten by
	       a new permutation determined by partial pivoting or diagonal
	       threshold pivoting.
	    Otherwise, perm_r is output argument;</pre><p>
<pre> L	    (output) SuperMatrix*
	    The factor L from the factorization Pr*A=L*U; use compressed row
	    subscripts storage for supernodes, i.e., L has type:
	    Stype = SLU_SC, Dtype = SLU_D, Mtype = SLU_TRLU.</pre><p>
<pre> U	    (output) SuperMatrix*
	    The factor U from the factorization Pr*A*Pc=L*U. Use column-wise
	    storage scheme, i.e., U has types: Stype = SLU_NC,
	    Dtype = SLU_D, Mtype = SLU_TRU.</pre><p>
<pre> stat     (output) SuperLUStat_t*
	    Record the statistics on runtime and floating-point operation count.
	    See <a class="el" href="slu__util_8h.html" title="Utility header file.">slu_util.h</a> for the definition of 'SuperLUStat_t'.</pre><p>
<pre> info     (output) int*
	    = 0: successful exit
	    &lt; 0: if info = -i, the i-th argument had an illegal value
	    &gt; 0: if info = i, and i is
	       &lt;= A-&gt;ncol: number of zero pivots. They are replaced by small
		  entries according to options-&gt;ILU_FillTol.
	       &gt; A-&gt;ncol: number of bytes allocated when memory allocation
		  failure occurred, plus A-&gt;ncol. If lwork = -1, it is
		  the estimated amount of space needed, plus A-&gt;ncol.</pre><p>
<pre> ======================================================================</pre><p>
<pre> Local Working Arrays:
 ======================
   m = number of rows in the matrix
   n = number of columns in the matrix</pre><p>
<pre>   marker[0:3*m-1]: marker[i] = j means that node i has been
	reached when working on column j.
	Storage: relative to original row subscripts
	NOTE: There are 4 of them:
	      marker/marker1 are used for panel dfs, see (ilu_)<a class="el" href="dpanel__dfs_8c.html" title="Peforms a symbolic factorization on a panel of symbols.">dpanel_dfs.c</a>;
	      marker2 is used for inner-factorization, see (ilu)_dcolumn_dfs.c;
	      marker_relax(has its own space) is used for relaxed supernodes.</pre><p>
<pre>   parent[0:m-1]: parent vector used during dfs
	Storage: relative to new row subscripts</pre><p>
<pre>   xplore[0:m-1]: xplore[i] gives the location of the next (dfs)
	unexplored neighbor of i in lsub[*]</pre><p>
<pre>   segrep[0:nseg-1]: contains the list of supernodal representatives
	in topological order of the dfs. A supernode representative is the
	last column of a supernode.
	The maximum size of segrep[] is n.</pre><p>
<pre>   repfnz[0:W*m-1]: for a nonzero segment U[*,j] that ends at a
	supernodal representative r, repfnz[r] is the location of the first
	nonzero in this segment.  It is also used during the dfs: repfnz[r]&gt;0
	indicates the supernode r has been explored.
	NOTE: There are W of them, each used for one column of a panel.</pre><p>
<pre>   panel_lsub[0:W*m-1]: temporary for the nonzeros row indices below
	the panel diagonal. These are filled in during <a class="el" href="dpanel__dfs_8c.html#2a809488b87d2c1a9b2a574b726e8517">dpanel_dfs()</a>, and are
	used later in the inner LU factorization within the panel.
	panel_lsub[]/dense[] pair forms the SPA data structure.
	NOTE: There are W of them.</pre><p>
<pre>   dense[0:W*m-1]: sparse accumulating (SPA) vector for intermediate values;
		   NOTE: there are W of them.</pre><p>
<pre>   tempv[0:*]: real temporary used for dense numeric kernels;
	The size of this array is defined by <a class="el" href="slu__util_8h.html#06193b28f40a4779ae7737711642eb45">NUM_TEMPV()</a> in <a class="el" href="slu__util_8h.html" title="Utility header file.">slu_util.h</a>.
	It is also used by the dropping routine <a class="el" href="ilu__ddrop__row_8c.html#380317801e05b11930fd1e094db34179">ilu_ddrop_row()</a>.
 </pre> 
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