text: #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 */
  }
  