78 lines
2.1 KiB
C
78 lines
2.1 KiB
C
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/*=============================================================================
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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) 2012 Sebastian Pancratz
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Copyright (C) 2013 Mike Hansen
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******************************************************************************/
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#include "fq.h"
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void
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_fq_trace(fmpz_t rop, const fmpz * op, slong len, const fq_ctx_t ctx)
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{
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const slong d = fq_ctx_degree(ctx);
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slong i, l;
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fmpz *t;
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t = _fmpz_vec_init(d);
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fmpz_set_ui(t + 0, d);
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for (i = 1; i < d; i++)
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{
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for (l = ctx->len - 2; l >= 0 && ctx->j[l] >= d - (i - 1); l--)
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{
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fmpz_addmul(t + i, t + (ctx->j[l] + i - d), ctx->a + l);
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}
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if (l >= 0 && ctx->j[l] == d - i)
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{
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fmpz_addmul_ui(t + i, ctx->a + l, i);
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}
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fmpz_neg(t + i, t + i);
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fmpz_mod(t + i, t + i, fq_ctx_prime(ctx));
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}
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fmpz_zero(rop);
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for (i = 0; i < d; i++)
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{
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fmpz_addmul(rop, op + i, t + i);
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}
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fmpz_mod(rop, rop, fq_ctx_prime(ctx));
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_fmpz_vec_clear(t, d);
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}
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void
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fq_trace(fmpz_t rop, const fq_t op, const fq_ctx_t ctx)
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{
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if (fq_is_zero(op, ctx))
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{
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fmpz_zero(rop);
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}
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else
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{
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_fq_trace(rop, op->coeffs, op->length, ctx);
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}
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}
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