167 lines
5.0 KiB
C
167 lines
5.0 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) 2011 William Hart
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Copyright (C) 2012 Andres Goens
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Copyright (C) 2013 Mike Hansen
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******************************************************************************/
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#ifdef T
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#include "templates.h"
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#include <stdlib.h>
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slong
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_TEMPLATE(T, poly_gcd_euclidean) (TEMPLATE(T, struct) * G,
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const TEMPLATE(T, struct) * A, slong lenA,
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const TEMPLATE(T, struct) * B, slong lenB,
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const TEMPLATE(T, t) invB,
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const TEMPLATE(T, ctx_t) ctx)
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{
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if (lenB == 1)
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{
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TEMPLATE(T, one) (G, ctx);
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return 1;
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}
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else /* lenA >= lenB > 1 */
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{
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const slong lenW = FLINT_MAX(lenA - lenB + 1, lenB) + lenA + 2 * lenB;
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TEMPLATE(T, t) invR3;
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TEMPLATE(T, struct) * Q, *R1, *R2, *R3, *T, *W;
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slong lenR2, lenR3;
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W = _TEMPLATE(T, vec_init) (lenW, ctx);
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Q = W;
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R1 = W + FLINT_MAX(lenA - lenB + 1, lenB);
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R2 = R1 + lenA;
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R3 = R2 + lenB;
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_TEMPLATE(T, poly_divrem) (Q, R1, A, lenA, B, lenB, invB, ctx);
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lenR3 = lenB - 1;
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TEMPLATE(CAP_T, VEC_NORM) (R1, lenR3, ctx);
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if (lenR3 == 0)
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{
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_TEMPLATE(T, vec_set) (G, B, lenB, ctx);
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_TEMPLATE(T, vec_clear) (W, lenW, ctx);
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return lenB;
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}
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TEMPLATE(T, init) (invR3, ctx);
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T = R3;
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R3 = R1;
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R1 = T;
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_TEMPLATE(T, vec_set) (R2, B, lenB, ctx);
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lenR2 = lenB;
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do
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{
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TEMPLATE(T, inv) (invR3, R3 + (lenR3 - 1), ctx);
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_TEMPLATE(T, poly_divrem) (Q, R1, R2, lenR2, R3, lenR3, invR3,
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ctx);
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lenR2 = lenR3--;
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TEMPLATE(CAP_T, VEC_NORM) (R1, lenR3, ctx);
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T = R2;
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R2 = R3;
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R3 = R1;
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R1 = T;
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}
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while (lenR3 > 0);
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_TEMPLATE(T, vec_set) (G, R2, lenR2, ctx);
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_TEMPLATE(T, vec_clear) (W, lenW, ctx);
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TEMPLATE(T, clear) (invR3, ctx);
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return lenR2;
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}
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}
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void
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TEMPLATE(T, poly_gcd_euclidean) (TEMPLATE(T, poly_t) G,
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const TEMPLATE(T, poly_t) A,
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const TEMPLATE(T, poly_t) B,
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const TEMPLATE(T, ctx_t) ctx)
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{
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if (A->length < B->length)
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{
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TEMPLATE(T, poly_gcd_euclidean) (G, B, A, ctx);
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}
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else /* lenA >= lenB >= 0 */
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{
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slong lenA = A->length, lenB = B->length, lenG;
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TEMPLATE(T, t) invB;
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TEMPLATE(T, struct) * g;
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if (lenA == 0) /* lenA = lenB = 0 */
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{
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TEMPLATE(T, poly_zero) (G, ctx);
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}
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else if (lenB == 0) /* lenA > lenB = 0 */
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{
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TEMPLATE(T, poly_make_monic) (G, A, ctx);
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}
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else /* lenA >= lenB >= 1 */
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{
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if (G == A || G == B)
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{
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g = _TEMPLATE(T, vec_init) (FLINT_MIN(lenA, lenB), ctx);
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}
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else
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{
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TEMPLATE(T, poly_fit_length) (G, FLINT_MIN(lenA, lenB), ctx);
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g = G->coeffs;
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}
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TEMPLATE(T, init) (invB, ctx);
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TEMPLATE(T, inv) (invB, TEMPLATE(T, poly_lead) (B, ctx), ctx);
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lenG = _TEMPLATE(T, poly_gcd_euclidean) (g, A->coeffs, lenA,
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B->coeffs, lenB, invB,
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ctx);
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TEMPLATE(T, clear) (invB, ctx);
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if (G == A || G == B)
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{
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_TEMPLATE(T, vec_clear) (G->coeffs, G->alloc, ctx);
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G->coeffs = g;
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G->alloc = FLINT_MIN(lenA, lenB);
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G->length = FLINT_MIN(lenA, lenB);
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}
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_TEMPLATE(T, poly_set_length) (G, lenG, ctx);
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if (G->length == 1)
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TEMPLATE(T, one) (G->coeffs, ctx);
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else
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TEMPLATE(T, poly_make_monic) (G, G, ctx);
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}
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}
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}
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#endif
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