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#include "cs.h"
/* C = A(P,Q) where P and Q are permutations of 0..m-1 and 0..n-1. */
cs *cs_permute (const cs *A, const int *Pinv, const int *Q, int values)
{
int p, j, k, nz = 0, m, n, *Ap, *Ai, *Cp, *Ci ;
double *Cx, *Ax ;
cs *C ;
if (!A) return (NULL) ; /* check inputs */
m = A->m ; n = A->n ; Ap = A->p ; Ai = A->i ; Ax = A->x ;
C = cs_spalloc (m, n, Ap [n], values && Ax != NULL, 0) ;
if (!C) return (cs_done (C, NULL, NULL, 0)) ; /* out of memory */
Cp = C->p ; Ci = C->i ; Cx = C->x ;
for (k = 0 ; k < n ; k++)
{
Cp [k] = nz ; /* column k of C is column Q[k] of A */
j = Q ? (Q [k]) : k ;
for (p = Ap [j] ; p < Ap [j+1] ; p++)
{
if (Cx) Cx [nz] = Ax [p] ; /* row i of A is row Pinv[i] of C */
Ci [nz++] = Pinv ? (Pinv [Ai [p]]) : Ai [p] ;
}
}
Cp [n] = nz ; /* finalize the last column of C */
return (cs_done (C, NULL, NULL, 1)) ;
}
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