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Annotation of gforth/engine/atanh.c, revision 1.7

1.1       anton       1: /* replacement for asinh, acosh, and atanh */
                      2: 
1.2       anton       3: /* 
1.7     ! anton       4:   Copyright (C) 1996,2000,2003,2007 Free Software Foundation, Inc.
1.2       anton       5: 
                      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
1.6       anton      10:   as published by the Free Software Foundation, either version 3
1.2       anton      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
1.6       anton      19:   along with this program; if not, see http://www.gnu.org/licenses/.
1.2       anton      20: */
                     21: 
1.1       anton      22: #include <math.h>
                     23: 
                     24: double atanh(double r1)
                     25: {
                     26:   double r2=r1 < 0 ? -r1 : r1;
                     27:   double r3=log((r2/(1.0-r2)*2)+1)/2;
                     28: 
                     29:   return r1 < 0 ? -r3 : r3;
                     30:   /* fdup f0< >r fabs 1. d>f fover f- f/  f2* flnp1 f2/
                     31:      r> IF  fnegate  THEN ;
                     32:      */
                     33: }
                     34: 
                     35: double asinh(double r1)
                     36: {
                     37:   return atanh(r1/sqrt(1.0+r1*r1));
                     38:   /* fdup fdup f* 1. d>f f+ fsqrt f/ fatanh ; */
                     39: }
                     40: 
                     41: double acosh(double r1)
                     42: {
                     43:   return(log(r1+sqrt(r1*r1-1.0)));
                     44:   /* fdup fdup f* 1. d>f f- fsqrt f+ fln ; */
                     45: }