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/*! @file zsnode_dfs.c
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 * \brief Determines the union of row structures of columns within the relaxed node
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 *
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 * 
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 * -- SuperLU routine (version 2.0) --
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 * Univ. of California Berkeley, Xerox Palo Alto Research Center,
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 * and Lawrence Berkeley National Lab.
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 * November 15, 1997
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 *
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 * Copyright (c) 1994 by Xerox Corporation.  All rights reserved.
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 *
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 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY
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 * EXPRESSED OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
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 * 
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 * Permission is hereby granted to use or copy this program for any
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 * purpose, provided the above notices are retained on all copies.
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 * Permission to modify the code and to distribute modified code is
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 * granted, provided the above notices are retained, and a notice that
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 * the code was modified is included with the above copyright notice.
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 * 
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 */
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#include "slu_zdefs.h"
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/*! \brief
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 *
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 * 
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 * Purpose
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 * =======
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 *    zsnode_dfs() - Determine the union of the row structures of those 
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 *    columns within the relaxed snode.
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 *    Note: The relaxed snodes are leaves of the supernodal etree, therefore, 
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 *    the portion outside the rectangular supernode must be zero.
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 *
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 * Return value
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 * ============
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 *     0   success;
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 *    >0   number of bytes allocated when run out of memory.
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 * 
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 */
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int
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zsnode_dfs (
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	   const int  jcol,	    /* in - start of the supernode */
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	   const int  kcol, 	    /* in - end of the supernode */
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	   const int  *asub,        /* in */
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	   const int  *xa_begin,    /* in */
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	   const int  *xa_end,      /* in */
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	   int        *xprune,      /* out */
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	   int        *marker,      /* modified */
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	   GlobalLU_t *Glu          /* modified */
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	   )
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{
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    register int i, k, ifrom, ito, nextl, new_next;
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    int          nsuper, krow, kmark, mem_error;
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    int          *xsup, *supno;
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    int          *lsub, *xlsub;
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    int          nzlmax;
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    xsup    = Glu->xsup;
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    supno   = Glu->supno;
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    lsub    = Glu->lsub;
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    xlsub   = Glu->xlsub;
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    nzlmax  = Glu->nzlmax;
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    nsuper = ++supno[jcol];	/* Next available supernode number */
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    nextl = xlsub[jcol];
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    for (i = jcol; i <= kcol; i++) {
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	/* For each nonzero in A[*,i] */
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	for (k = xa_begin[i]; k < xa_end[i]; k++) {	
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	    krow = asub[k];
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	    kmark = marker[krow];
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	    if ( kmark != kcol ) { /* First time visit krow */
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		marker[krow] = kcol;
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		lsub[nextl++] = krow;
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		if ( nextl >= nzlmax ) {
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		    if ( mem_error = zLUMemXpand(jcol, nextl, LSUB, &nzlmax, Glu) )
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			return (mem_error);
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		    lsub = Glu->lsub;
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		}
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	    }
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    	}
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	supno[i] = nsuper;
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    }
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    /* Supernode > 1, then make a copy of the subscripts for pruning */
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    if ( jcol < kcol ) {
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	new_next = nextl + (nextl - xlsub[jcol]);
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	while ( new_next > nzlmax ) {
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	    if ( mem_error = zLUMemXpand(jcol, nextl, LSUB, &nzlmax, Glu) )
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		return (mem_error);
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	    lsub = Glu->lsub;
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	}
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	ito = nextl;
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	for (ifrom = xlsub[jcol]; ifrom < nextl; )
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	    lsub[ito++] = lsub[ifrom++];	
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        for (i = jcol+1; i <= kcol; i++) xlsub[i] = nextl;
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	nextl = ito;
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    }
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    xsup[nsuper+1] = kcol + 1;
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    supno[kcol+1]  = nsuper;
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    xprune[kcol]   = nextl;
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    xlsub[kcol+1]  = nextl;
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    return 0;
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}
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