arb/acb_modular/psl2z_mul.c
2014-10-01 15:25:50 +02:00

61 lines
1.8 KiB
C

/*=============================================================================
This file is part of ARB.
ARB 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.
ARB 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 ARB; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
=============================================================================*/
/******************************************************************************
Copyright (C) 2014 Fredrik Johansson
******************************************************************************/
#include "acb_modular.h"
void
psl2z_mul(psl2z_t h, const psl2z_t f, const psl2z_t g)
{
if (h == f || h == g)
{
psl2z_t t;
psl2z_init(t);
psl2z_mul(t, f, g);
psl2z_swap(t, h);
psl2z_clear(t);
return;
}
fmpz_mul(&h->a, &f->a, &g->a);
fmpz_addmul(&h->a, &f->b, &g->c);
fmpz_mul(&h->b, &f->a, &g->b);
fmpz_addmul(&h->b, &f->b, &g->d);
fmpz_mul(&h->c, &f->c, &g->a);
fmpz_addmul(&h->c, &f->d, &g->c);
fmpz_mul(&h->d, &f->c, &g->b);
fmpz_addmul(&h->d, &f->d, &g->d);
if (fmpz_sgn(&h->c) < 0 || (fmpz_is_zero(&h->c) && fmpz_sgn(&h->d) < 0))
{
fmpz_neg(&h->a, &h->a);
fmpz_neg(&h->b, &h->b);
fmpz_neg(&h->c, &h->c);
fmpz_neg(&h->d, &h->d);
}
}