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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta http-equiv="Content-Type" content="text/html;charset=iso-8859-1"><title>SuperLU: SRC/sgstrf.c File Reference</title><link href="doxygen.css" rel="stylesheet" type="text/css"><link href="tabs.css" rel="stylesheet" type="text/css"></head><body><!-- Generated by Doxygen 1.4.6 --><div class="tabs"> <ul> <li><a href="index.html"><span>Main Page</span></a></li> <li><a href="annotated.html"><span>Data Structures</span></a></li> <li id="current"><a href="files.html"><span>Files</span></a></li> </ul></div><div class="tabs"> <ul> <li><a href="files.html"><span>File List</span></a></li> <li><a href="globals.html"><span>Globals</span></a></li> </ul></div><h1>SRC/sgstrf.c File Reference</h1>Computes an LU factorization of a general sparse matrix. <a href="#_details">More...</a><p><code>#include "<a class="el" href="slu__sdefs_8h-source.html">slu_sdefs.h</a>"</code><br><table border="0" cellpadding="0" cellspacing="0"><tr><td></td></tr><tr><td colspan="2"><br><h2>Functions</h2></td></tr><tr><td class="memItemLeft" nowrap align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="sgstrf_8c.html#5e0aa16101f1984f2e54567cd092f9c5">sgstrf</a> (<a class="el" href="structsuperlu__options__t.html">superlu_options_t</a> *options, <a class="el" href="structSuperMatrix.html">SuperMatrix</a> *A, float drop_tol, 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></table><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="5e0aa16101f1984f2e54567cd092f9c5"></a><!-- doxytag: member="sgstrf.c::sgstrf" ref="5e0aa16101f1984f2e54567cd092f9c5" args="(superlu_options_t *options, SuperMatrix *A, float drop_tol, 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)" --><p><table class="mdTable" cellpadding="2" cellspacing="0"> <tr> <td class="mdRow"> <table cellpadding="0" cellspacing="0" border="0"> <tr> <td class="md" nowrap valign="top">void sgstrf </td> <td class="md" valign="top">( </td> <td class="md" nowrap valign="top"><a class="el" href="structsuperlu__options__t.html">superlu_options_t</a> * </td> <td class="mdname" nowrap> <em>options</em>, </td> </tr> <tr> <td class="md" nowrap align="right"></td> <td class="md"></td> <td class="md" nowrap><a class="el" href="structSuperMatrix.html">SuperMatrix</a> * </td> <td class="mdname" nowrap> <em>A</em>, </td> </tr> <tr> <td class="md" nowrap align="right"></td> <td class="md"></td> <td class="md" nowrap>float </td> <td class="mdname" nowrap> <em>drop_tol</em>, </td> </tr> <tr> <td class="md" nowrap align="right"></td> <td class="md"></td> <td class="md" nowrap>int </td> <td class="mdname" nowrap> <em>relax</em>, </td> </tr> <tr> <td class="md" nowrap align="right"></td> <td class="md"></td> <td class="md" nowrap>int </td> <td class="mdname" nowrap> <em>panel_size</em>, </td> </tr> <tr> <td class="md" nowrap align="right"></td> <td class="md"></td> <td class="md" nowrap>int * </td> <td class="mdname" nowrap> <em>etree</em>, </td> </tr> <tr> <td class="md" nowrap align="right"></td> <td class="md"></td> <td class="md" nowrap>void * </td> <td class="mdname" nowrap> <em>work</em>, </td> </tr> <tr> <td class="md" nowrap align="right"></td> <td class="md"></td> <td class="md" nowrap>int </td> <td class="mdname" nowrap> <em>lwork</em>, </td> </tr> <tr> <td class="md" nowrap align="right"></td> <td class="md"></td> <td class="md" nowrap>int * </td> <td class="mdname" nowrap> <em>perm_c</em>, </td> </tr> <tr> <td class="md" nowrap align="right"></td> <td class="md"></td> <td class="md" nowrap>int * </td> <td class="mdname" nowrap> <em>perm_r</em>, </td> </tr> <tr> <td class="md" nowrap align="right"></td> <td class="md"></td> <td class="md" nowrap><a class="el" href="structSuperMatrix.html">SuperMatrix</a> * </td> <td class="mdname" nowrap> <em>L</em>, </td> </tr> <tr> <td class="md" nowrap align="right"></td> <td class="md"></td> <td class="md" nowrap><a class="el" href="structSuperMatrix.html">SuperMatrix</a> * </td> <td class="mdname" nowrap> <em>U</em>, </td> </tr> <tr> <td class="md" nowrap align="right"></td> <td class="md"></td> <td class="md" nowrap><a class="el" href="structSuperLUStat__t.html">SuperLUStat_t</a> * </td> <td class="mdname" nowrap> <em>stat</em>, </td> </tr> <tr> <td class="md" nowrap align="right"></td> <td class="md"></td> <td class="md" nowrap>int * </td> <td class="mdname" nowrap> <em>info</em></td> </tr> <tr> <td class="md"></td> <td class="md">) </td> <td class="md" colspan="2"></td> </tr> </table> </td> </tr></table><table cellspacing="5" cellpadding="0" border="0"> <tr> <td> </td> <td><p><pre> Purpose =======</pre><p><pre> SGSTRF computes an LU 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->nrow > A->ncol), and U is upper triangular (upper trapezoidal if A->nrow < A->ncol).</pre><p><pre> See <a class="el" href="supermatrix_8h.html">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 LU decomposition will be performed.</pre><p><pre> A (input) SuperMatrix* Original matrix A, permuted by columns, of dimension (A->nrow, A->ncol). The type of A can be: Stype = SLU_NCP; Dtype = SLU_S; Mtype = SLU_GE.</pre><p><pre> drop_tol (input) float (NOT IMPLEMENTED) Drop tolerance parameter. At step j of the Gaussian elimination, if <a class="el" href="slamch_8c.html#3aa069ac3980707dae1e0530f50d59e4">abs(A_ij)</a>/(max_i <a class="el" href="slamch_8c.html#3aa069ac3980707dae1e0530f50d59e4">abs(A_ij)</a>) < drop_tol, drop entry A_ij. 0 <= drop_tol <= 1. The default value of drop_tol is 0.</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->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->ncol-1; etree[root]==A->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; > 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->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->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->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_S, 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_S, Mtype = SLU_TRU.</pre><p><pre> stat (output) SuperLUStat_t* Record the statistics on runtime and floating-point operation count. See util.h for the definition of 'SuperLUStat_t'.</pre><p><pre> info (output) int* = 0: successful exit < 0: if info = -i, the i-th argument had an illegal value > 0: if info = i, and i is <= A->ncol: U(i,i) is exactly zero. The factorization has been completed, but the factor U is exactly singular, and division by zero will occur if it is used to solve a system of equations. > A->ncol: number of bytes allocated when memory allocation failure occurred, plus A->ncol. If lwork = -1, it is the estimated amount of space needed, plus A->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> xprune[0:n-1]: xprune[*] points to locations in subscript vector lsub[*]. For column i, xprune[i] denotes the point where structural pruning begins. I.e. only xlsub[i],..,xprune[i]-1 need to be traversed for symbolic factorization.</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 3 of them: marker/marker1 are used for panel dfs, see <a class="el" href="spanel__dfs_8c.html">spanel_dfs.c</a>; marker2 is used for inner-factorization, see <a class="el" href="scolumn__dfs_8c.html">scolumn_dfs.c</a>.</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]>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="slu__sdefs_8h.html#77baf210393e04fa71d4e73b5e60e556">spanel_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__sdefs_8h.html">slu_sdefs.h</a>. </pre> </td> </tr></table><hr size="1"><address style="align: right;"><small>Generated on Fri Aug 1 22:40:40 2008 for SuperLU by <a href="http://www.doxygen.org/index.html"><img src="doxygen.png" alt="doxygen" align="middle" border="0"></a> 1.4.6 </small></address></body></html>⌨️ 快捷键说明
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