libStatGen Software  1
MapFunction.cpp
1 /*
2  * Copyright (C) 2010 Regents of the University of Michigan
3  *
4  * This program is free software: you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License as published by
6  * the Free Software Foundation, either version 3 of the License, or
7  * (at your option) any later version.
8  *
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12  * GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program. If not, see <http://www.gnu.org/licenses/>.
16  */
17 
18 #include "MapFunction.h"
19 #include "MathConstant.h"
20 
21 #include <math.h>
22 
23 double DistanceToRecombination(double distance)
24 {
25  return (1.0 - exp(-2.0 * distance)) * 0.5;
26 }
27 
28 double RecombinationToDistance(double recombination)
29 {
30  return (log(max(1.0 - 2 * recombination, 1e-7)) * -0.5);
31 }
32 
33 double KosambiDistanceToRecombination(double distance)
34 {
35  double e_to_4x = exp(4.0 * distance);
36 
37  return (0.5 *(e_to_4x - 1.0) / (e_to_4x + 1.0));
38 }
39 
40 double RecombinationToKosambiDistance(double theta)
41 {
42  return 0.25 * log((1.0 + 2*theta) / max(1.0 - 2.0*theta, 1e-7));
43 }