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/*=============================================================================
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) 2011, 2012 Sebastian Pancratz
Copyright (C) 2012 Andres Goens
Copyright (C) 2013 Mike Hansen
******************************************************************************/
#include "fq_nmod.h"
void _fq_nmod_inv(mp_limb_t *rop, const mp_limb_t *op, slong len,
const fq_nmod_ctx_t ctx)
{
const slong d = fq_nmod_ctx_degree(ctx);
if (len == 1)
{
rop[0] = n_invmod(op[0], ctx->mod.n);
_nmod_vec_zero(rop + 1, d - 1);
}
else
{
_nmod_poly_invmod(rop, op, len, ctx->modulus->coeffs, d + 1, ctx->mod);
}
}
void fq_nmod_inv(fq_nmod_t rop, const fq_nmod_t op, const fq_nmod_ctx_t ctx)
{
if (fq_nmod_is_zero(op, ctx))
{
flint_printf("Exception (fq_nmod_inv). Zero is not invertible.\n");
abort();
}
else
{
const slong d = fq_nmod_ctx_degree(ctx);
mp_limb_t *t;
if (rop == op)
{
t = _nmod_vec_init(d);
}
else
{
nmod_poly_fit_length(rop, d);
t = rop->coeffs;
}
_fq_nmod_inv(t, op->coeffs, op->length, ctx);
if (rop == op)
{
_nmod_vec_clear(rop->coeffs);
rop->coeffs = t;
rop->alloc = d;
rop->length = d;
}
else
{
_nmod_poly_set_length(rop, d);
}
_nmod_poly_normalise(rop);
}
}
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