143 lines
3.3 KiB
C
143 lines
3.3 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) 2011 Fredrik Johansson
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******************************************************************************/
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#include "fmpq.h"
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void
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_fmpq_sub(fmpz_t rnum, fmpz_t rden, const fmpz_t p, const fmpz_t q,
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const fmpz_t r, const fmpz_t s)
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{
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fmpz_t g, a, b, t, u;
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/* Same denominator */
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if (fmpz_equal(q, s))
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{
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fmpz_sub(rnum, p, r);
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/* Both are integers */
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if (fmpz_is_one(q))
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{
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fmpz_set(rden, q);
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}
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else
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{
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fmpz_init(g);
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fmpz_gcd(g, rnum, q);
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if (fmpz_is_one(g))
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{
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fmpz_set(rden, q);
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}
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else
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{
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fmpz_divexact(rnum, rnum, g);
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fmpz_divexact(rden, q, g);
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}
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fmpz_clear(g);
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}
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return;
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}
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/* p/q is an integer */
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if (fmpz_is_one(q))
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{
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fmpz_init(t);
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fmpz_mul(t, p, s);
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fmpz_sub(rnum, t, r);
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fmpz_set(rden, s);
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fmpz_clear(t);
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return;
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}
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/* r/s is an integer */
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if (fmpz_is_one(s))
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{
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fmpz_init(t);
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fmpz_mul(t, r, q);
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fmpz_sub(rnum, p, t);
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fmpz_set(rden, q);
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fmpz_clear(t);
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return;
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}
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fmpz_init(g);
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fmpz_gcd(g, q, s);
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if (fmpz_is_one(g))
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{
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fmpz_init(t);
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fmpz_init(u);
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fmpz_mul(t, p, s);
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fmpz_mul(u, q, r);
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fmpz_sub(rnum, t, u);
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fmpz_mul(rden, q, s);
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fmpz_clear(t);
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fmpz_clear(u);
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}
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else
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{
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fmpz_init(a);
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fmpz_init(b);
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fmpz_init(t);
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fmpz_init(u);
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fmpz_divexact(a, q, g);
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fmpz_divexact(b, s, g);
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fmpz_mul(t, p, b);
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fmpz_mul(u, r, a);
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fmpz_sub(rnum, t, u);
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fmpz_gcd(t, rnum, g);
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if (fmpz_is_one(t))
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{
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fmpz_mul(rden, q, b);
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}
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else
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{
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fmpz_divexact(rnum, rnum, t);
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fmpz_divexact(g, q, t);
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fmpz_mul(rden, g, b);
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}
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fmpz_clear(a);
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fmpz_clear(b);
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fmpz_clear(t);
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fmpz_clear(u);
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}
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fmpz_clear(g);
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}
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void fmpq_sub(fmpq_t res, const fmpq_t op1, const fmpq_t op2)
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{
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_fmpq_sub(fmpq_numref(res), fmpq_denref(res),
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fmpq_numref(op1), fmpq_denref(op1),
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fmpq_numref(op2), fmpq_denref(op2));
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}
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