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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_vec.h"
#include "fmpq_mpoly.h"
int fmpq_mpoly_compose_fmpq_mpoly(fmpq_mpoly_t A,
const fmpq_mpoly_t B, fmpq_mpoly_struct * const * C,
const fmpq_mpoly_ctx_t ctxB, const fmpq_mpoly_ctx_t ctxAC)
{
int success = 0;
slong i;
fmpq * scales;
fmpz_mpoly_struct ** Czpoly;
fmpz_mpoly_t newB;
slong nvarsB = ctxB->zctx->minfo->nvars;
TMP_INIT;
if (fmpq_mpoly_is_zero(B, ctxB))
{
fmpq_mpoly_zero(A, ctxAC);
return 1;
}
TMP_START;
Czpoly = (fmpz_mpoly_struct **) TMP_ALLOC(nvarsB*sizeof(fmpz_mpoly_struct *));
/*
scale B by the contents of the polynomials in C
We are only borrowing B to feed it to fmpz_mpoly_compose.
There might be zero coeffs in newBcoeffs, but fmpz_mpoly_compose
should have no problem with zero coeffs.
*/
scales = (fmpq *) TMP_ALLOC(nvarsB*sizeof(fmpq));
for (i = 0; i < nvarsB; i++)
{
Czpoly[i] = C[i]->zpoly;
/* we are only borrowing the content of each of the C[i] */
*(scales + i) = *C[i]->content;
}
*newB = *B->zpoly;
newB->coeffs = _fmpz_vec_init(B->zpoly->length);
if (!_fmpq_mpoly_rescale(A->content, newB->coeffs, B, scales, ctxB))
goto cleanup;
if (!fmpz_mpoly_compose_fmpz_mpoly(A->zpoly, newB, Czpoly,
ctxB->zctx, ctxAC->zctx))
goto cleanup;
fmpq_mpoly_reduce(A, ctxAC);
success = 1;
cleanup:
TMP_END;
_fmpz_vec_clear(newB->coeffs, B->zpoly->length);
return success;
}