29 lines
1.3 KiB
C
29 lines
1.3 KiB
C
#include "cs.h"
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/* C = alpha*A + beta*B */
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cs *cs_add (const cs *A, const cs *B, double alpha, double beta)
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{
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int p, j, nz = 0, anz, *Cp, *Ci, *Bp, m, n, bnz, *w, values ;
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double *x, *Bx, *Cx ;
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cs *C ;
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if (!CS_CSC (A) || !CS_CSC (B)) return (NULL) ; /* check inputs */
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if (A->m != B->m || A->n != B->n) return (NULL) ;
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m = A->m ; anz = A->p [A->n] ;
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n = B->n ; Bp = B->p ; Bx = B->x ; bnz = Bp [n] ;
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w = cs_calloc (m, sizeof (int)) ; /* get workspace */
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values = (A->x != NULL) && (Bx != NULL) ;
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x = values ? cs_malloc (m, sizeof (double)) : NULL ; /* get workspace */
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C = cs_spalloc (m, n, anz + bnz, values, 0) ; /* allocate result*/
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if (!C || !w || (values && !x)) return (cs_done (C, w, x, 0)) ;
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Cp = C->p ; Ci = C->i ; Cx = C->x ;
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for (j = 0 ; j < n ; j++)
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{
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Cp [j] = nz ; /* column j of C starts here */
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nz = cs_scatter (A, j, alpha, w, x, j+1, C, nz) ; /* alpha*A(:,j)*/
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nz = cs_scatter (B, j, beta, w, x, j+1, C, nz) ; /* beta*B(:,j) */
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if (values) for (p = Cp [j] ; p < nz ; p++) Cx [p] = x [Ci [p]] ;
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}
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Cp [n] = nz ; /* finalize the last column of C */
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cs_sprealloc (C, 0) ; /* remove extra space from C */
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return (cs_done (C, w, x, 1)) ; /* success; free workspace, return C */
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}
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