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/*
Copyright (C) 2018 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 "fmpz.h"
#include "mpoly.h"
#include "fmpz_mpoly.h"
/*
assuming that the exponents are valid and sorted,
put the polynomial in canonical form
i.e.
2*x^e + 3*x^e -> 5x^e
2*x^e - 2*x^e -> 0
*/
void fmpz_mpoly_combine_like_terms(fmpz_mpoly_t A, const fmpz_mpoly_ctx_t ctx)
{
slong in, out, N = mpoly_words_per_exp(A->bits, ctx->minfo);
out = -WORD(1);
for (in = WORD(0); in < A->length; in++)
{
FLINT_ASSERT(in > out);
if (out >= WORD(0) &&
mpoly_monomial_equal(A->exps + N*out, A->exps + N*in, N))
{
fmpz_add(A->coeffs + out, A->coeffs + out, A->coeffs + in);
} else
{
if (out < WORD(0) || !fmpz_is_zero(A->coeffs + out))
out++;
if (out != in)
{
mpoly_monomial_set(A->exps + N*out, A->exps + N*in, N);
fmpz_swap(A->coeffs + out, A->coeffs + in);
}
}
}
if (out < WORD(0) || !fmpz_is_zero(A->coeffs + out))
out++;
_fmpz_mpoly_set_length(A, out, ctx);
}