88 lines
2.5 KiB
C
88 lines
2.5 KiB
C
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/*=============================================================================
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This file is part of FLINT.
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FLINT 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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FLINT 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 FLINT; 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) 2010 William Hart
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Copyright (C) 2010 Sebastian Pancratz
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******************************************************************************/
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#include <gmp.h>
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#include "flint.h"
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#include "fmpz.h"
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#include "fmpz_vec.h"
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void
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_fmpz_vec_scalar_submul_si_2exp(fmpz * vec1, const fmpz * vec2, slong len2,
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slong c, ulong exp)
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{
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slong i;
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fmpz_t temp;
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if (c == 0)
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return; /* nothing to add */
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if (exp == 0) /* just do submul */
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{
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_fmpz_vec_scalar_submul_si(vec1, vec2, len2, c);
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return;
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}
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fmpz_init(temp);
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if (c == 1) /* scalar is 1, just subtract c * 2^exp times c */
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{
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for (i = 0; i < len2; i++)
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{
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fmpz_mul_2exp(temp, vec2 + i, exp);
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fmpz_sub(vec1 + i, vec1 + i, temp);
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}
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}
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else if (c == -1) /* scalar is -1, add c * 2^exp */
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{
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for (i = 0; i < len2; i++)
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{
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fmpz_mul_2exp(temp, vec2 + i, exp);
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fmpz_add(vec1 + i, vec1 + i, temp);
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}
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}
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else /* generic case */
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{
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if (c >= 0)
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{
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for (i = 0; i < len2; i++)
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{
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fmpz_mul_2exp(temp, vec2 + i, exp);
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fmpz_submul_ui(vec1 + i, temp, c);
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}
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}
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else
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{
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for (i = 0; i < len2; i++)
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{
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fmpz_mul_2exp(temp, vec2 + i, exp);
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fmpz_addmul_ui(vec1 + i, temp, -c);
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}
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}
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}
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fmpz_clear(temp);
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}
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