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// CXSparse/Source/cs_dupl: remove duplicates from a sparse matrix
// CXSparse, Copyright (c) 2006-2022, Timothy A. Davis. All Rights Reserved.
// SPDX-License-Identifier: LGPL-2.1+
#include "cs.h"
/* remove duplicate entries from A */
CS_INT cs_dupl (cs *A)
{
CS_INT i, j, p, q, nz = 0, n, m, *Ap, *Ai, *w ;
CS_ENTRY *Ax ;
if (!CS_CSC (A)) return (0) ; /* check inputs */
m = A->m ; n = A->n ; Ap = A->p ; Ai = A->i ; Ax = A->x ;
w = cs_malloc (m, sizeof (CS_INT)) ; /* get workspace */
if (!w) return (0) ; /* out of memory */
for (i = 0 ; i < m ; i++) w [i] = -1 ; /* row i not yet seen */
for (j = 0 ; j < n ; j++)
{
q = nz ; /* column j will start at q */
for (p = Ap [j] ; p < Ap [j+1] ; p++)
{
i = Ai [p] ; /* A(i,j) is nonzero */
if (w [i] >= q)
{
Ax [w [i]] += Ax [p] ; /* A(i,j) is a duplicate */
}
else
{
w [i] = nz ; /* record where row i occurs */
Ai [nz] = i ; /* keep A(i,j) */
Ax [nz++] = Ax [p] ;
}
}
Ap [j] = q ; /* record start of column j */
}
Ap [n] = nz ; /* finalize A */
cs_free (w) ; /* free workspace */
return (cs_sprealloc (A, 0)) ; /* remove extra space from A */
}
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