1/* mpc_atanh -- inverse hyperbolic tangent of a complex number.
2
3Copyright (C) 2009, 2011, 2012 INRIA
4
5This file is part of GNU MPC.
6
7GNU MPC is free software; you can redistribute it and/or modify it under
8the terms of the GNU Lesser General Public License as published by the
9Free Software Foundation; either version 3 of the License, or (at your
10option) any later version.
11
12GNU MPC is distributed in the hope that it will be useful, but WITHOUT ANY
13WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
14FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
15more details.
16
17You should have received a copy of the GNU Lesser General Public License
18along with this program. If not, see http://www.gnu.org/licenses/ .
19*/
20
21#include "mpc-impl.h"
22
23int
24mpc_atanh (mpc_ptr rop, mpc_srcptr op, mpc_rnd_t rnd)
25{
26  /* atanh(op) = -i*atan(i*op) */
27  int inex;
28  mpfr_t tmp;
29  mpc_t z, a;
30
31  mpc_realref (z)[0] = mpc_imagref (op)[0];
32  mpc_imagref (z)[0] = mpc_realref (op)[0];
33  MPFR_CHANGE_SIGN (mpc_realref (z));
34
35  /* Note reversal of precisions due to later multiplication by -i */
36  mpc_init3 (a, MPC_PREC_IM(rop), MPC_PREC_RE(rop));
37
38  inex = mpc_atan (a, z,
39                   MPC_RND (INV_RND (MPC_RND_IM (rnd)), MPC_RND_RE (rnd)));
40
41  /* change a to -i*a, i.e., x+i*y to y-i*x */
42  tmp[0] = mpc_realref (a)[0];
43  mpc_realref (a)[0] = mpc_imagref (a)[0];
44  mpc_imagref (a)[0] = tmp[0];
45  MPFR_CHANGE_SIGN (mpc_imagref (a));
46
47  mpc_set (rop, a, rnd);
48
49  mpc_clear (a);
50
51  return MPC_INEX (MPC_INEX_IM (inex), -MPC_INEX_RE (inex));
52}
53