138 lines
4.3 KiB
C
138 lines
4.3 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) 2010, 2011 Sebastian Pancratz
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******************************************************************************/
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#include "fmpq_poly.h"
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#include "fmpz_poly_q.h"
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void fmpz_poly_q_div(fmpz_poly_q_t rop,
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const fmpz_poly_q_t op1, const fmpz_poly_q_t op2)
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{
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if (fmpz_poly_q_is_zero(op2))
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{
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flint_printf("Exception (fmpz_poly_q_div). Division by zero.\n");
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abort();
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}
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if (fmpz_poly_q_is_zero(op1))
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{
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fmpz_poly_q_zero(rop);
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return;
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}
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if (op1 == op2)
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{
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fmpz_poly_q_one(rop);
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return;
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}
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if (rop == op1 || rop == op2)
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{
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fmpz_poly_q_t t;
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fmpz_poly_q_init(t);
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fmpz_poly_q_div(t, op1, op2);
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fmpz_poly_q_swap(rop, t);
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fmpz_poly_q_clear(t);
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return;
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}
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/*
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From here on, we know that rop, op1 and op2 refer to distinct objects
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in memory, and that op1 and op2 are non-zero rational functions
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*/
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/*
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XXX: Do not maintain the remaining part of the function separately!!!
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Instead, note that this is the same as the corresponding part of
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the multiplication code, with op2->num and op2->den swapped.
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The only caveat to this is that we cannot assume the leading
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coefficient of op2->num to be positive, and thus check for this
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in the very end.
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*/
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/* Denominator/ numerator equal to one? */
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if (fmpz_poly_is_one(op1->den) && fmpz_poly_is_one(op2->num))
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{
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fmpz_poly_mul(rop->num, op1->num, op2->den);
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fmpz_poly_set_si(rop->den, 1);
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return;
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}
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fmpz_poly_gcd(rop->num, op1->num, op2->num);
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if (fmpz_poly_is_one(rop->num))
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{
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fmpz_poly_gcd(rop->den, op2->den, op1->den);
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if (fmpz_poly_is_one(rop->den))
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{
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fmpz_poly_mul(rop->num, op1->num, op2->den);
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fmpz_poly_mul(rop->den, op1->den, op2->num);
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}
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else
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{
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fmpz_poly_div(rop->num, op2->den, rop->den);
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fmpz_poly_mul(rop->num, op1->num, rop->num);
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fmpz_poly_div(rop->den, op1->den, rop->den);
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fmpz_poly_mul(rop->den, rop->den, op2->num);
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}
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}
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else
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{
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fmpz_poly_gcd(rop->den, op2->den, op1->den);
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if (fmpz_poly_is_one(rop->den))
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{
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fmpz_poly_div(rop->den, op2->num, rop->num);
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fmpz_poly_mul(rop->den, op1->den, rop->den);
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fmpz_poly_div(rop->num, op1->num, rop->num);
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fmpz_poly_mul(rop->num, rop->num, op2->den);
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}
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else
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{
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fmpz_poly_t t, u;
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fmpz_poly_init(t);
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fmpz_poly_init(u);
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fmpz_poly_div(t, op1->num, rop->num);
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fmpz_poly_div(u, op2->num, rop->num);
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fmpz_poly_div(rop->num, op2->den, rop->den);
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fmpz_poly_mul(rop->num, t, rop->num);
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fmpz_poly_div(rop->den, op1->den, rop->den);
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fmpz_poly_mul(rop->den, rop->den, u);
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fmpz_poly_clear(t);
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fmpz_poly_clear(u);
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}
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}
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/* XXX: Check that the numerator has the appropriate sign. */
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if (fmpz_sgn(fmpz_poly_lead(rop->den)) < 0)
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{
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fmpz_poly_neg(rop->num, rop->num);
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fmpz_poly_neg(rop->den, rop->den);
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}
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}
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