1 /*
2 Copyright (C) 2015 Fredrik Johansson
3
4 This file is part of Arb.
5
6 Arb is free software: you can redistribute it and/or modify it under
7 the terms of the GNU Lesser General Public License (LGPL) as published
8 by the Free Software Foundation; either version 2.1 of the License, or
9 (at your option) any later version. See <http://www.gnu.org/licenses/>.
10 */
11
12 #include "arb.h"
13
14 void
arb_atanh(arb_t z,const arb_t x,slong prec)15 arb_atanh(arb_t z, const arb_t x, slong prec)
16 {
17 if (arb_is_zero(x))
18 {
19 arb_zero(z);
20 }
21 else
22 {
23 arb_t t;
24 arb_init(t);
25
26 arb_sub_ui(t, x, 1, prec + 4);
27 arb_div(t, x, t, prec + 4);
28 arb_mul_2exp_si(t, t, 1);
29 arb_neg(t, t);
30 arb_log1p(z, t, prec);
31 arb_mul_2exp_si(z, z, -1);
32
33 arb_clear(t);
34 }
35 }
36
37