/* Copyright (C) 2011, 2012 Sebastian Pancratz Copyright (C) 2012 Andres Goens Copyright (C) 2013 Mike Hansen This file is part of FLINT. FLINT is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License (LGPL) as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. See . */ #include "fq.h" void _fq_inv(fmpz * rop, const fmpz * op, slong len, const fq_ctx_t ctx) { const slong d = fq_ctx_degree(ctx); if (len == 1) { fmpz_invmod(rop, op, fq_ctx_prime(ctx)); _fmpz_vec_zero(rop + 1, d - 1); } else { _fmpz_mod_poly_invmod(rop, op, len, ctx->modulus->coeffs, d + 1, fq_ctx_prime(ctx)); } } void fq_inv(fq_t rop, const fq_t op, const fq_ctx_t ctx) { if (fq_is_zero(op, ctx)) { flint_printf("Exception (fq_inv). Zero is not invertible.\n"); flint_abort(); } else { const slong d = fq_ctx_degree(ctx); fmpz *t; if (rop == op) { t = _fmpz_vec_init(d); } else { fmpz_poly_fit_length(rop, d); t = rop->coeffs; } _fq_inv(t, op->coeffs, op->length, ctx); if (rop == op) { _fmpz_vec_clear(rop->coeffs, rop->alloc); rop->coeffs = t; rop->alloc = d; rop->length = d; } else { _fmpz_poly_set_length(rop, d); } _fmpz_poly_normalise(rop); } }