cs_counts.c
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00001 #include "cs.h"
00002 /* column counts of LL'=A or LL'=A'A, given parent & post ordering */
00003 #define HEAD(k,j) (ata ? head [k] : j)
00004 #define NEXT(J)   (ata ? next [J] : -1)
00005 static void init_ata (cs *AT, const int *post, int *w, int **head, int **next)
00006 {
00007     int i, k, p, m = AT->n, n = AT->m, *ATp = AT->p, *ATi = AT->i ;
00008     *head = w+4*n, *next = w+5*n+1 ;
00009     for (k = 0 ; k < n ; k++) w [post [k]] = k ;    /* invert post */
00010     for (i = 0 ; i < m ; i++)
00011     {
00012         for (k = n, p = ATp[i] ; p < ATp[i+1] ; p++) k = CS_MIN (k, w [ATi[p]]);
00013         (*next) [i] = (*head) [k] ;     /* place row i in linked list k */
00014         (*head) [k] = i ;
00015     }
00016 }
00017 int *cs_counts (const cs *A, const int *parent, const int *post, int ata)
00018 {
00019     int i, j, k, n, m, J, s, p, q, jleaf, *ATp, *ATi, *maxfirst, *prevleaf,
00020         *ancestor, *head = NULL, *next = NULL, *colcount, *w, *first, *delta ;
00021     cs *AT ;
00022     if (!CS_CSC (A) || !parent || !post) return (NULL) ;    /* check inputs */
00023     m = A->m ; n = A->n ;
00024     s = 4*n + (ata ? (n+m+1) : 0) ;
00025     delta = colcount = cs_malloc (n, sizeof (int)) ;    /* allocate result */
00026     w = cs_malloc (s, sizeof (int)) ;                   /* get workspace */
00027     AT = cs_transpose (A, 0) ;                          /* AT = A' */
00028     if (!AT || !colcount || !w) return (cs_idone (colcount, AT, w, 0)) ;
00029     ancestor = w ; maxfirst = w+n ; prevleaf = w+2*n ; first = w+3*n ;
00030     for (k = 0 ; k < s ; k++) w [k] = -1 ;      /* clear workspace w [0..s-1] */
00031     for (k = 0 ; k < n ; k++)                   /* find first [j] */
00032     {
00033         j = post [k] ;
00034         delta [j] = (first [j] == -1) ? 1 : 0 ;  /* delta[j]=1 if j is a leaf */
00035         for ( ; j != -1 && first [j] == -1 ; j = parent [j]) first [j] = k ;
00036     }
00037     ATp = AT->p ; ATi = AT->i ;
00038     if (ata) init_ata (AT, post, w, &head, &next) ;
00039     for (i = 0 ; i < n ; i++) ancestor [i] = i ; /* each node in its own set */
00040     for (k = 0 ; k < n ; k++)
00041     {
00042         j = post [k] ;          /* j is the kth node in postordered etree */
00043         if (parent [j] != -1) delta [parent [j]]-- ;    /* j is not a root */
00044         for (J = HEAD (k,j) ; J != -1 ; J = NEXT (J))   /* J=j for LL'=A case */
00045         {
00046             for (p = ATp [J] ; p < ATp [J+1] ; p++)
00047             {
00048                 i = ATi [p] ;
00049                 q = cs_leaf (i, j, first, maxfirst, prevleaf, ancestor, &jleaf);
00050                 if (jleaf >= 1) delta [j]++ ;   /* A(i,j) is in skeleton */
00051                 if (jleaf == 2) delta [q]-- ;   /* account for overlap in q */
00052             }
00053         }
00054         if (parent [j] != -1) ancestor [j] = parent [j] ;
00055     }
00056     for (j = 0 ; j < n ; j++)           /* sum up delta's of each child */
00057     {
00058         if (parent [j] != -1) colcount [parent [j]] += colcount [j] ;
00059     }
00060     return (cs_idone (colcount, AT, w, 1)) ;    /* success: free workspace */
00061 } 
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hogman_minimal
Author(s): Maintained by Juergen Sturm
autogenerated on Wed Dec 26 2012 15:36:47