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

52 lines
1.6 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) 2013 Mike Hansen
******************************************************************************/
#include "fq_zech.h"
void
fq_zech_pth_root(fq_zech_t rop, const fq_zech_t op1, const fq_zech_ctx_t ctx)
{
slong i, d;
mp_limb_t e;
double qm1inv;
if (fq_zech_is_zero(op1, ctx) || fq_zech_is_one(op1, ctx))
{
rop->value = op1->value;
return;
}
d = fq_zech_ctx_degree(ctx) - 1;
qm1inv = n_precompute_inverse(ctx->qm1);
e = op1->value;
for (i = 0; i < d; i++)
{
e = n_mulmod_precomp(ctx->p, e, ctx->qm1, qm1inv);
}
rop->value = e;
}