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