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00001 #include "cs.h" 00002 /* C = A(p,p) where A and C are symmetric the upper part stored; pinv not p */ 00003 cs *cs_symperm (const cs *A, const int *pinv, int values) 00004 { 00005 int i, j, p, q, i2, j2, n, *Ap, *Ai, *Cp, *Ci, *w ; 00006 double *Cx, *Ax ; 00007 cs *C ; 00008 if (!CS_CSC (A)) return (NULL) ; /* check inputs */ 00009 n = A->n ; Ap = A->p ; Ai = A->i ; Ax = A->x ; 00010 C = cs_spalloc (n, n, Ap [n], values && (Ax != NULL), 0) ; /* alloc result*/ 00011 w = cs_calloc (n, sizeof (int)) ; /* get workspace */ 00012 if (!C || !w) return (cs_done (C, w, NULL, 0)) ; /* out of memory */ 00013 Cp = C->p ; Ci = C->i ; Cx = C->x ; 00014 for (j = 0 ; j < n ; j++) /* count entries in each column of C */ 00015 { 00016 j2 = pinv ? pinv [j] : j ; /* column j of A is column j2 of C */ 00017 for (p = Ap [j] ; p < Ap [j+1] ; p++) 00018 { 00019 i = Ai [p] ; 00020 if (i > j) continue ; /* skip lower triangular part of A */ 00021 i2 = pinv ? pinv [i] : i ; /* row i of A is row i2 of C */ 00022 w [CS_MAX (i2, j2)]++ ; /* column count of C */ 00023 } 00024 } 00025 cs_cumsum (Cp, w, n) ; /* compute column pointers of C */ 00026 for (j = 0 ; j < n ; j++) 00027 { 00028 j2 = pinv ? pinv [j] : j ; /* column j of A is column j2 of C */ 00029 for (p = Ap [j] ; p < Ap [j+1] ; p++) 00030 { 00031 i = Ai [p] ; 00032 if (i > j) continue ; /* skip lower triangular part of A*/ 00033 i2 = pinv ? pinv [i] : i ; /* row i of A is row i2 of C */ 00034 Ci [q = w [CS_MAX (i2, j2)]++] = CS_MIN (i2, j2) ; 00035 if (Cx) Cx [q] = Ax [p] ; 00036 } 00037 } 00038 return (cs_done (C, w, NULL, 1)) ; /* success; free workspace, return C */ 00039 }