mirror of
https://github.com/vale981/arb
synced 2025-03-06 18:01:39 -05:00
68 lines
2 KiB
C
68 lines
2 KiB
C
/*=============================================================================
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This file is part of ARB.
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ARB is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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ARB is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with ARB; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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=============================================================================*/
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/******************************************************************************
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Copyright (C) 2012 Fredrik Johansson
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******************************************************************************/
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#include "fmpz_holonomic.h"
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void
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fmpz_holonomic_get_nth_fmpz(fmpz_t res, const fmpz_holonomic_t op, const fmpz * initial, long n0, long n)
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{
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long r = fmpz_holonomic_order(op);
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if (r == 0)
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{
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fmpz_zero(res);
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return;
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}
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else if (n < n0)
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{
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printf("not implemented\n");
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abort();
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}
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else if (n - n0 < r)
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{
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fmpz_set(res, initial + n - n0);
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return;
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}
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else
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{
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fmpz_mat_t M;
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long i;
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fmpz_t Q;
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fmpz_mat_init(M, r, r);
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fmpz_init(Q);
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fmpz_holonomic_forward_fmpz_mat(M, Q, op, n0, n - n0 - r + 1);
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fmpz_mul(fmpz_mat_entry(M, r - 1, 0), fmpz_mat_entry(M, r - 1, 0), initial + 0);
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for (i = 1; i < r; i++)
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fmpz_addmul(fmpz_mat_entry(M, r - 1, 0), fmpz_mat_entry(M, r - 1, i), initial + i);
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fmpz_divexact(res, fmpz_mat_entry(M, r - 1, 0), Q);
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fmpz_mat_clear(M);
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fmpz_clear(Q);
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}
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}
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