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#include "cs.h"
/* C = compressed-column form of a triplet matrix T */
cs *cs_compress (const cs *T)
{
int m, n, nz, p, k, *Cp, *Ci, *w, *Ti, *Tj ;
double *Cx, *Tx ;
cs *C ;
if (!CS_TRIPLET (T)) return (NULL) ; /* check inputs */
m = T->m ; n = T->n ; Ti = T->i ; Tj = T->p ; Tx = T->x ; nz = T->nz ;
C = cs_spalloc (m, n, nz, Tx != NULL, 0) ; /* allocate result */
w = cs_calloc (n, sizeof (int)) ; /* get workspace */
if (!C || !w) return (cs_done (C, w, NULL, 0)) ; /* out of memory */
Cp = C->p ; Ci = C->i ; Cx = C->x ;
for (k = 0 ; k < nz ; k++) w [Tj [k]]++ ; /* column counts */
cs_cumsum (Cp, w, n) ; /* column pointers */
for (k = 0 ; k < nz ; k++)
{
Ci [p = w [Tj [k]]++] = Ti [k] ; /* A(i,j) is the pth entry in C */
if (Cx) Cx [p] = Tx [k] ;
}
return (cs_done (C, w, NULL, 1)) ; /* success; free w and return C */
}
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