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.fft;
39
40 import static org.junit.Assert.assertEquals;
41
42 import java.util.Arrays;
43 import java.util.Collection;
44 import java.util.Random;
45
46 import ffx.utilities.FFXTest;
47 import org.junit.Test;
48 import org.junit.runner.RunWith;
49 import org.junit.runners.Parameterized;
50 import org.junit.runners.Parameterized.Parameters;
51
52 /** @author Michael J. Schnieders */
53 @RunWith(Parameterized.class)
54 public class RealTest extends FFXTest {
55
56 private final int n;
57 private final String info;
58 private final double[] data;
59 private final double[] complexData;
60 private final double[] expected;
61
62 public RealTest(String info, int n) {
63 this.info = info;
64 this.n = n;
65 assert (n % 2 == 0);
66 int paddedN = n + 2;
67 data = new double[paddedN];
68 complexData = new double[n * 2];
69 expected = new double[n];
70 Random r = new Random();
71 for (int i = 0; i < n; i++) {
72 double d = r.nextDouble();
73 data[i] = d;
74 complexData[i * 2] = d;
75 expected[i] = d;
76 }
77 }
78
79 @Parameters
80 public static Collection<Object[]> data() {
81 return Arrays.asList(
82 new Object[][] {{"Test n = 20", 20}, {"Test n = 22", 22}, {"Test n = 120", 120}});
83 }
84
85 /** Test of fft method, of class Complex. */
86 @Test
87 public void testFft() {
88 double tolerance = 1.0e-13;
89
90 int offset = 0;
91 int stride = 2;
92 Real real = new Real(n);
93 Complex complex = new Complex(n);
94 real.fft(data, offset);
95 complex.fft(complexData, offset, stride);
96 for (int i = 0; i < n; i++) {
97 double expect = complexData[i];
98 double actual = data[i];
99 assertEquals(info + " @ " + i, expect, actual, tolerance);
100 }
101 real.inverse(data, offset);
102 for (int i = 0; i < n; i++) {
103 double orig = expected[i];
104 double actual = data[i];
105 assertEquals(info, orig, actual, tolerance);
106 }
107 }
108 }