63 lines
1.8 KiB
C
63 lines
1.8 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) 2013 Mike Hansen
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******************************************************************************/
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#include "fq_zech.h"
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void
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fq_zech_trace(fmpz_t rop, const fq_zech_t op, const fq_zech_ctx_t ctx)
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{
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mp_limb_t p_i, trace;
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fq_zech_t t, op_p_i;
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double qm1inv;
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if (fq_zech_is_zero(op, ctx))
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{
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fmpz_zero(rop);
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return;
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}
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fq_zech_zero(t, ctx);
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qm1inv = n_precompute_inverse(ctx->qm1);
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for (p_i = 1; p_i <= ctx->qm1; p_i *= ctx->p)
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{
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/* op_q_i = op ^ (p ^ i) */
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op_p_i->value = n_mulmod_precomp(op->value, p_i, ctx->qm1, qm1inv);
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/* t += op_p_i */
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fq_zech_add(t, t, op_p_i, ctx);
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}
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if (fq_zech_is_zero(t, 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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trace = t->value / ctx->qm1opm1;
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trace = n_powmod(ctx->prime_root, trace, ctx->p);
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fmpz_set_ui(rop, trace);
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}
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}
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