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.numerics.special;
39
40 import java.util.Arrays;
41 import java.util.Collection;
42
43 import ffx.utilities.FFXTest;
44 import org.junit.Assert;
45 import org.junit.Test;
46 import org.junit.runner.RunWith;
47 import org.junit.runners.Parameterized;
48 import org.junit.runners.Parameterized.Parameters;
49
50 /** @author Michael J. Schnieders */
51 @RunWith(Parameterized.class)
52 public class ModifiedBesselTest extends FFXTest {
53
54 /**
55 * The implementation of the Modified 0th and 1st Order Bessel functions pass for a tolerance of
56 * 1.0e-15.
57 */
58 private final String info;
59 private final double x;
60 private final double i0;
61 private final double i1;
62 private final double tolerance = 1e-15;
63
64 public ModifiedBesselTest(String info, double x, double i0, double i1) {
65 this.info = info;
66 this.x = x;
67 this.i0 = i0;
68 this.i1 = i1;
69 }
70
71 /**
72 * The expected values were found to 20 decimal points of precision using Mathematica:
73 * SetPrecision[BesselI[0, x], 20]] SetPrecision[BesselI[1, x], 20]]
74 */
75 @Parameters
76 public static Collection<Object[]> data() {
77 return Arrays.asList(
78 new Object[][] {
79 {"Test 0.0", 0.0, 1.0, 0.0},
80 {"Test 1.0", 1.0, 1.2660658777520081841, 0.56515910399248503460},
81 {"Test -1.0", -1.0, 1.2660658777520081841, -0.56515910399248503460},
82 {"Test 4.0", 4.0, 11.301921952136330773, 9.7594651537044505574},
83 {"Test -4.0", -4.0, 11.301921952136330773, -9.7594651537044505574},
84 {"Test 7.9", 7.9, 389.40628328215802867, 363.85394408450838455},
85 {"Test -7.9", -7.9, 389.40628328215802867, -363.85394408450838455},
86 {"Test 8.0", 8.0, 427.56411572180473968, 399.87313678256009553},
87 {"Test -8.0", -8.0, 427.56411572180473968, -399.87313678256009553},
88 {"Test 8.0001", 8.0001, 427.60410492344237809, 399.91089657459764339},
89 {"Test -8.0001", -8.0001, 427.60410492344237809, -399.91089657459764339},
90 {"Test 10.0", 10.0, 2815.7166284662530416, 2670.9883037012536988},
91 {"Test -10.0", -10.0, 2815.7166284662530416, -2670.9883037012536988}
92 });
93 }
94
95 /** Test of erf method, of class Erf. */
96 @Test
97 public void testZeroOrderModifiedBessel() {
98 double actual = ModifiedBessel.i0(x);
99 Assert.assertEquals(info, i0 / actual, 1.0, tolerance);
100 }
101
102 /** Test of erfc method, of class Erf. */
103 @Test
104 public void testFirstOrderModifiedBessel() {
105 double actual = ModifiedBessel.i1(x);
106 if (actual != 0.0) {
107 Assert.assertEquals(info, i1 / actual, 1.0, tolerance);
108 } else {
109 Assert.assertEquals(info, i1, actual, tolerance);
110 }
111 }
112 }