1 #include "cs.h"
2 /* C = compressed-column form of a triplet matrix T */
cs_compress(const cs * T)3 cs *cs_compress (const cs *T)
4 {
5 CS_INT m, n, nz, p, k, *Cp, *Ci, *w, *Ti, *Tj ;
6 CS_ENTRY *Cx, *Tx ;
7 cs *C ;
8 if (!CS_TRIPLET (T)) return (NULL) ; /* check inputs */
9 m = T->m ; n = T->n ; Ti = T->i ; Tj = T->p ; Tx = T->x ; nz = T->nz ;
10 C = cs_spalloc (m, n, nz, Tx != NULL, 0) ; /* allocate result */
11 w = cs_calloc (n, sizeof (CS_INT)) ; /* get workspace */
12 if (!C || !w) return (cs_done (C, w, NULL, 0)) ; /* out of memory */
13 Cp = C->p ; Ci = C->i ; Cx = C->x ;
14 for (k = 0 ; k < nz ; k++) w [Tj [k]]++ ; /* column counts */
15 cs_cumsum (Cp, w, n) ; /* column pointers */
16 for (k = 0 ; k < nz ; k++)
17 {
18 Ci [p = w [Tj [k]]++] = Ti [k] ; /* A(i,j) is the pth entry in C */
19 if (Cx) Cx [p] = Tx [k] ;
20 }
21 return (cs_done (C, w, NULL, 1)) ; /* success; free w and return C */
22 }
23