145 lines
4.0 KiB
C
145 lines
4.0 KiB
C
/*=============================================================================
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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) 2008, 2009 William Hart
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Copyright (C) 2010 Sebastian Pancratz
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******************************************************************************/
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#include <stdlib.h>
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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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#include "fmpz_poly.h"
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void
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_fmpz_poly_mullow_KS(fmpz * res, const fmpz * poly1, slong len1,
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const fmpz * poly2, slong len2, slong n)
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{
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int neg1, neg2;
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slong limbs1, limbs2, loglen;
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slong bits1, bits2, bits;
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mp_limb_t *arr1, *arr2, *arr3;
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slong sign = 0;
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FMPZ_VEC_NORM(poly1, len1);
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FMPZ_VEC_NORM(poly2, len2);
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if (!len1 | !len2)
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{
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_fmpz_vec_zero(res, n);
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return;
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}
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neg1 = (fmpz_sgn(poly1 + len1 - 1) > 0) ? 0 : -1;
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neg2 = (fmpz_sgn(poly2 + len2 - 1) > 0) ? 0 : -1;
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if (n > len1 + len2 - 1)
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{
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_fmpz_vec_zero(res + len1 + len2 - 1, n - (len1 + len2 - 1));
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n = len1 + len2 - 1;
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}
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bits1 = _fmpz_vec_max_bits(poly1, len1);
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if (bits1 < 0)
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{
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sign = 1;
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bits1 = -bits1;
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}
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if (poly1 != poly2)
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{
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bits2 = _fmpz_vec_max_bits(poly2, len2);
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if (bits2 < 0)
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{
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sign = 1;
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bits2 = -bits2;
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}
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}
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else
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bits2 = bits1;
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loglen = FLINT_BIT_COUNT(FLINT_MIN(len1, len2));
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bits = bits1 + bits2 + loglen + sign;
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limbs1 = (bits * len1 - 1) / FLINT_BITS + 1;
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limbs2 = (bits * len2 - 1) / FLINT_BITS + 1;
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if (poly1 == poly2)
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{
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arr1 = (mp_ptr) flint_calloc(limbs1, sizeof(mp_limb_t));
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arr2 = arr1;
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_fmpz_poly_bit_pack(arr1, poly1, len1, bits, neg1);
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}
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else
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{
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arr1 = (mp_ptr) flint_calloc(limbs1 + limbs2, sizeof(mp_limb_t));
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arr2 = arr1 + limbs1;
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_fmpz_poly_bit_pack(arr1, poly1, len1, bits, neg1);
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_fmpz_poly_bit_pack(arr2, poly2, len2, bits, neg2);
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}
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arr3 = (mp_ptr) flint_malloc((limbs1 + limbs2) * sizeof(mp_limb_t));
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if (limbs1 == limbs2)
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mpn_mul_n(arr3, arr1, arr2, limbs1);
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else if (limbs1 > limbs2)
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mpn_mul(arr3, arr1, limbs1, arr2, limbs2);
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else
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mpn_mul(arr3, arr2, limbs2, arr1, limbs1);
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if (sign)
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_fmpz_poly_bit_unpack(res, n, arr3, bits, neg1 ^ neg2);
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else
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_fmpz_poly_bit_unpack_unsigned(res, n, arr3, bits);
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flint_free(arr1);
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flint_free(arr3);
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}
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void
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fmpz_poly_mullow_KS(fmpz_poly_t res,
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const fmpz_poly_t poly1, const fmpz_poly_t poly2, slong n)
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{
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const slong len1 = poly1->length;
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const slong len2 = poly2->length;
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if (len1 == 0 || len2 == 0 || n == 0)
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{
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fmpz_poly_zero(res);
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}
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else
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{
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fmpz_poly_fit_length(res, n);
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if (len1 >= len2)
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_fmpz_poly_mullow_KS(res->coeffs, poly1->coeffs, len1,
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poly2->coeffs, len2, n);
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else
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_fmpz_poly_mullow_KS(res->coeffs, poly2->coeffs, len2,
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poly1->coeffs, len1, n);
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_fmpz_poly_set_length(res, n);
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_fmpz_poly_normalise(res);
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}
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}
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