pqc/external/flint-2.4.3/qadic/trace.c
2014-05-24 23:16:06 +02:00

91 lines
2.4 KiB
C

/*=============================================================================
This file is part of FLINT.
FLINT is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
FLINT is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with FLINT; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
=============================================================================*/
/******************************************************************************
Copyright (C) 2012 Sebastian Pancratz
******************************************************************************/
#include "qadic.h"
void _qadic_trace(fmpz_t rop, const fmpz *op, slong len,
const fmpz *a, const slong *j, slong lena, const fmpz_t pN)
{
const slong d = j[lena - 1];
slong i, l;
fmpz *t;
t = _fmpz_vec_init(d);
fmpz_set_ui(t + 0, d);
for (i = 1; i < d; i++)
{
for (l = lena - 2; l >= 0 && j[l] >= d - (i - 1); l--)
{
fmpz_addmul(t + i, t + (j[l] + i - d), a + l);
}
if (l >= 0 && j[l] == d - i)
{
fmpz_addmul_ui(t + i, a + l, i);
}
fmpz_neg(t + i, t + i);
fmpz_mod(t + i, t + i, pN);
}
fmpz_zero(rop);
for (i = 0; i < d; i++)
{
fmpz_addmul(rop, op + i, t + i);
}
fmpz_mod(rop, rop, pN);
_fmpz_vec_clear(t, d);
}
void qadic_trace(padic_t rop, const qadic_t op, const qadic_ctx_t ctx)
{
const slong N = padic_prec(rop);
if (qadic_is_zero(op) || op->val >= N)
{
padic_zero(rop);
}
else
{
fmpz_t pN;
int alloc;
alloc = _padic_ctx_pow_ui(pN, N - op->val, &ctx->pctx);
_qadic_trace(padic_unit(rop), op->coeffs, op->length,
ctx->a, ctx->j, ctx->len, pN);
padic_val(rop) = op->val;
_padic_canonicalise(rop, &ctx->pctx);
if (alloc)
fmpz_clear(pN);
}
}