arb/acb_modular/psl2z_inv.c
2016-04-26 17:20:05 +02:00

32 lines
743 B
C

/*
Copyright (C) 2014 Fredrik Johansson
This file is part of Arb.
Arb 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 <http://www.gnu.org/licenses/>.
*/
#include "acb_modular.h"
void
psl2z_inv(psl2z_t h, const psl2z_t g)
{
if (h != g)
psl2z_set(h, g);
if (fmpz_is_zero(&h->c) && fmpz_sgn(&h->a) > 0)
{
fmpz_neg(&h->b, &h->b);
fmpz_swap(&h->d, &h->a);
}
else
{
fmpz_swap(&h->a, &h->d);
fmpz_neg(&h->a, &h->a);
fmpz_neg(&h->d, &h->d);
}
}