1 // ******************************************************************************
2 //
3 // Title: Force Field X.
4 // Description: Force Field X - Software for Molecular Biophysics.
5 // Copyright: Copyright (c) Michael J. Schnieders 2001-2024.
6 //
7 // This file is part of Force Field X.
8 //
9 // Force Field X is free software; you can redistribute it and/or modify it
10 // under the terms of the GNU General Public License version 3 as published by
11 // the Free Software Foundation.
12 //
13 // Force Field X is distributed in the hope that it will be useful, but WITHOUT
14 // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
15 // FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
16 // details.
17 //
18 // You should have received a copy of the GNU General Public License along with
19 // Force Field X; if not, write to the Free Software Foundation, Inc., 59 Temple
20 // Place, Suite 330, Boston, MA 02111-1307 USA
21 //
22 // Linking this library statically or dynamically with other modules is making a
23 // combined work based on this library. Thus, the terms and conditions of the
24 // GNU General Public License cover the whole combination.
25 //
26 // As a special exception, the copyright holders of this library give you
27 // permission to link this library with independent modules to produce an
28 // executable, regardless of the license terms of these independent modules, and
29 // to copy and distribute the resulting executable under terms of your choice,
30 // provided that you also meet, for each linked independent module, the terms
31 // and conditions of the license of that module. An independent module is a
32 // module which is not derived from or based on this library. If you modify this
33 // library, you may extend this exception to your version of the library, but
34 // you are not obligated to do so. If you do not wish to do so, delete this
35 // exception statement from your version.
36 //
37 // ******************************************************************************
38 package ffx.algorithms.optimize.anneal;
39
40 /**
41 * Linear temperature schedule for simulated annealing
42 *
43 * @author Jacob M. Litman
44 * @author Michael J. Schnieders
45 * @since 1.0
46 */
47 public class LinearAnnealSchedule implements AnnealingSchedule {
48
49 private final int nWindows;
50 private final double tHigh;
51 private final double tLow;
52 private final double dTemp;
53 private final String description;
54
55 /**
56 * Creates an exponential annealing schedule that decays as tHigh-(n*(tHigh-tLow)).
57 *
58 * @param nWindows Number of windows.
59 * @param tLow Low temperature bound.
60 * @param tHigh High temperature bound.
61 */
62 public LinearAnnealSchedule(int nWindows, double tLow, double tHigh) {
63 assert nWindows > 1;
64 assert tLow < tHigh;
65 assert tLow >= 0;
66 assert Double.isFinite(tHigh);
67
68 this.nWindows = nWindows;
69 this.tHigh = tHigh;
70 this.tLow = tLow;
71 dTemp = (tLow - tHigh) / (nWindows - 1);
72
73 description = String.format("Linear annealing schedule with %d windows, "
74 + "initial temperature %12.7g K, final temperature %12.7g K, dT/window %12.7g K", nWindows,
75 tHigh, tLow, dTemp);
76 }
77
78 @Override
79 public double getHighTemp() {
80 return tHigh;
81 }
82
83 @Override
84 public double getLowTemp() {
85 return tLow;
86 }
87
88 @Override
89 public int getNumWindows() {
90 return nWindows;
91 }
92
93 @Override
94 public double getTemperature(int i) {
95 assert i >= 0 && i < nWindows;
96 return tHigh + (dTemp * i);
97 }
98
99 @Override
100 public double[] getTemperatures() {
101 double[] temps = new double[nWindows];
102 for (int i = 0; i < nWindows; i++) {
103 temps[i] = getTemperature(i);
104 }
105 return temps;
106 }
107
108 @Override
109 public double maxWindowLength() {
110 return 1.0;
111 }
112
113 @Override
114 public double minWindowLength() {
115 return 1.0;
116 }
117
118 @Override
119 public String toString() {
120 return description;
121 }
122
123 @Override
124 public double totalWindowLength() {
125 return nWindows;
126 }
127
128 @Override
129 public double windowLength(int window) {
130 return 1.0;
131 }
132 }