gforth: gforth/engine/atanh.c

1 :	anton	1.1	/* replacement for asinh, acosh, and atanh */
2 :
3 :	anton	1.2	/*
4 :	anton	1.4	Copyright (C) 1996,2000 Free Software Foundation, Inc.
5 :	anton	1.2
6 :			This file is part of Gforth.
7 :
8 :			Gforth is free software; you can redistribute it and/or
9 :			modify it under the terms of the GNU General Public License
10 :			as published by the Free Software Foundation; either version 2
11 :			of the License, or (at your option) any later version.
12 :
13 :			This program is distributed in the hope that it will be useful,
14 :			but WITHOUT ANY WARRANTY; without even the implied warranty of
15 :			MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 :			GNU General Public License for more details.
17 :
18 :			You should have received a copy of the GNU General Public License
19 :			along with this program; if not, write to the Free Software
20 :	anton	1.3	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
21 :	anton	1.2	*/
22 :
23 :	anton	1.1	#include <math.h>
24 :
25 :			double atanh(double r1)
26 :			{
27 :			double r2=r1 < 0 ? -r1 : r1;
28 :			double r3=log((r2/(1.0-r2)*2)+1)/2;
29 :
30 :			return r1 < 0 ? -r3 : r3;
31 :			/* fdup f0< >r fabs 1. d>f fover f- f/ f2* flnp1 f2/
32 :			r> IF fnegate THEN ;
33 :			*/
34 :			}
35 :
36 :			double asinh(double r1)
37 :			{
38 :			return atanh(r1/sqrt(1.0+r1*r1));
39 :			/* fdup fdup f* 1. d>f f+ fsqrt f/ fatanh ; */
40 :			}
41 :
42 :			double acosh(double r1)
43 :			{
44 :			return(log(r1+sqrt(r1*r1-1.0)));
45 :			/* fdup fdup f* 1. d>f f- fsqrt f+ fln ; */
46 :			}