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#include "cs.h"
/* x = x + beta * A(:,j), where x is a dense vector and A(:,j) is sparse */
int cs_scatter (const cs *A, int j, double beta, int *w, double *x, int mark,
cs *C, int nz)
{
int i, p, *Ap, *Ai, *Ci ;
double *Ax ;
if (!CS_CSC (A) || !w || !CS_CSC (C)) return (-1) ; /* check inputs */
Ap = A->p ; Ai = A->i ; Ax = A->x ; Ci = C->i ;
for (p = Ap [j] ; p < Ap [j+1] ; p++)
{
i = Ai [p] ; /* A(i,j) is nonzero */
if (w [i] < mark)
{
w [i] = mark ; /* i is new entry in column j */
Ci [nz++] = i ; /* add i to pattern of C(:,j) */
if (x) x [i] = beta * Ax [p] ; /* x(i) = beta*A(i,j) */
}
else if (x) x [i] += beta * Ax [p] ; /* i exists in C(:,j) already */
}
return (nz) ;
}
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