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/*
Copyright (C) 2018-2020 Daniel Schultz
This file is part of FLINT.
FLINT is free software: you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License (LGPL) as published
by the Free Software Foundation; either version 3 of the License, or
(at your option) any later version. See <https://www.gnu.org/licenses/>.
*/
#include "fmpq_mpoly.h"
void fmpq_mpoly_sub(fmpq_mpoly_t A, const fmpq_mpoly_t B,
const fmpq_mpoly_t C, const fmpq_mpoly_ctx_t ctx)
{
fmpz_t t1, t2;
slong easy_length = B->zpoly->length + C->zpoly->length;
if (fmpq_mpoly_is_zero(B, ctx))
{
fmpq_mpoly_neg(A, C, ctx);
return;
}
if (fmpq_mpoly_is_zero(C, ctx))
{
fmpq_mpoly_set(A, B, ctx);
return;
}
fmpz_init(t1);
fmpz_init(t2);
fmpq_gcd_cofactors(A->content, t1, t2, B->content, C->content);
fmpz_neg(t2, t2);
fmpz_mpoly_scalar_fmma(A->zpoly, B->zpoly, t1, C->zpoly, t2, ctx->zctx);
fmpz_clear(t1);
fmpz_clear(t2);
fmpq_mpoly_reduce_easy(A, easy_length, ctx);
}