1 files changed, 54 insertions, 0 deletions
diff --git a/elki/src/test/java/de/lmu/ifi/dbs/elki/math/SinCosTableTest.java b/elki/src/test/java/de/lmu/ifi/dbs/elki/math/SinCosTableTest.java
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+++ b/elki/src/test/java/de/lmu/ifi/dbs/elki/math/SinCosTableTest.java
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+package de.lmu.ifi.dbs.elki.math;
+/*
+ This file is part of ELKI:
+ Environment for Developing KDD-Applications Supported by Index-Structures
+
+ Copyright (C) 2015
+ Ludwig-Maximilians-Universität München
+ Lehr- und Forschungseinheit für Datenbanksysteme
+ ELKI Development Team
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU Affero General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU Affero General Public License for more details.
+
+ You should have received a copy of the GNU Affero General Public License
+ along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+
+import de.lmu.ifi.dbs.elki.JUnit4Test;
+
+/**
+ * Test the sin-cos lookup table.
+ *
+ * @author Erich Schubert
+ * @since 0.4.0
+ */
+public class SinCosTableTest implements JUnit4Test {
+  @Test
+  public void testSinCosTable() {
+    doSinCosTableTest(360);
+    doSinCosTableTest(142); // Divisible by two
+    doSinCosTableTest(17);
+    doSinCosTableTest(131); // Prime.
+  }
+
+  protected void doSinCosTableTest(int steps) {
+    SinCosTable table = SinCosTable.make(steps);
+    for(int i = -steps; i < 2 * steps; i++) {
+      double angle = Math.toRadians(360. * i / steps);
+      assertEquals("Cosine does not match at i=" + i + " a=" + angle, Math.cos(angle), table.cos(i), 1E-10);
+      assertEquals("Sine does not match at i=" + i + " a=" + angle, Math.sin(angle), table.sin(i), 1E-10);
+    }
+  }
+}