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