add triangular stream!

Author: Bruce

src/main/java/org/javasim/streams/TriangularStream.java

@@ -0,0 +1,92 @@
+/*
+ * Copyright 1990-2008, Mark Little, University of Newcastle upon Tyne
+ * and others contributors as indicated 
+ * by the @authors tag. All rights reserved. 
+ * See the copyright.txt in the distribution for a
+ * full listing of individual contributors. 
+ * This copyrighted material is made available to anyone wishing to use,
+ * modify, copy, or redistribute it subject to the terms and conditions
+ * of the GNU Lesser General Public License, v. 2.1.
+ * This program is distributed in the hope that it will be useful, but WITHOUT A 
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A 
+ * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
+ * You should have received a copy of the GNU Lesser General Public License,
+ * v.2.1 along with this distribution; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, 
+ * MA  02110-1301, USA.
+ * 
+ * (C) 1990-2008,
+ */
+
+package org.javasim.streams;
+
+import java.io.IOException;
+
+/**
+ * Returns a number drawn from a uniform distribution with the given lower and upper bounds.
+ */
+
+public class TriangularStream extends RandomStream {
+  /**
+   * Create stream with low bound 'l' and high bound 'h' and 'm' value.
+   */
+
+  public TriangularStream(double a, double b, double c) {
+    super();
+
+    this.a = a;
+    this.b = b;
+    this.c = c;
+  }
+
+  /**
+   * Create stream with low bound 'l' and high bound 'h' and 'm' value. Skip the first 'StreamSelect' values before returning numbers from the stream.
+   */
+
+  public TriangularStream(double a, double b, double c, int StreamSelect) {
+    super();
+
+    this.a = a;
+    this.b = b;
+    this.c = c;
+
+    for (int i = 0; i < StreamSelect * 1000; i++)
+      uniform();
+  }
+
+  /**
+   * Create stream with low bound 'l' and high bound 'h' and 'm' value. Skip the first 'StreamSelect' values before returning numbers from the stream. Pass the seeds 'MGSeed' and 'LCGSeed' to the base
+   * class.
+   */
+
+  public TriangularStream(double a, double b, double c, int StreamSelect, long MGSeed, long LCGSeed) {
+    super(MGSeed, LCGSeed);
+
+    this.a = a;
+    this.b = b;
+    this.c = c;
+
+    for (int i = 0; i < StreamSelect * 1000; i++)
+      uniform();
+  }
+
+  /**
+   * @return a number from the stream.
+   */
+
+  public double getNumber() throws IOException, ArithmeticException {
+
+    double F = (c - a) / (b - a);
+    double rand = uniform();
+    if (rand < F) {
+      return a + Math.sqrt(rand * (b - a) * (c - a));
+    } else {
+      return b - Math.sqrt((1 - rand) * (b - a) * (b - c));
+    }
+
+  }
+
+  private double a;
+  private double b;
+  private double c;
+}

src/test/java/org/javasim/examples/streams/TriangularExampleStreamTest.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright 1990-2008, Mark Little, University of Newcastle upon Tyne
+ * and others contributors as indicated 
+ * by the @authors tag. All rights reserved. 
+ * See the copyright.txt in the distribution for a
+ * full listing of individual contributors. 
+ * This copyrighted material is made available to anyone wishing to use,
+ * modify, copy, or redistribute it subject to the terms and conditions
+ * of the GNU Lesser General Public License, v. 2.1.
+ * This program is distributed in the hope that it will be useful, but WITHOUT A 
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A 
+ * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
+ * You should have received a copy of the GNU Lesser General Public License,
+ * v.2.1 along with this distribution; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, 
+ * MA  02110-1301, USA.
+ * 
+ * (C) 1990-2008,
+ */
+
+package org.javasim.examples.streams;
+
+import org.javasim.stats.Histogram;
+import org.javasim.streams.TriangularStream;
+import org.junit.Test;
+
+public class TriangularExampleStreamTest {
+  @Test
+  public void test() {
+    try {
+
+      TriangularStream triagular = new TriangularStream(0, 20, 7);
+
+      Histogram hist = new Histogram(25);
+
+      for (int i = 0; i < 10000; i++) {
+        int value = (int) Math.round(triagular.getNumber());
+
+        System.out.println(" " + value);
+
+        hist.setValue(value);
+      }
+
+      System.out.println("NormalStream error: " + triagular.error());
+
+      hist.print();
+
+    } catch (final Throwable ex) {
+    }
+  }
+}

src/test/java/org/javasim/tests/streams/TriangularStreamUnitTest.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright 1990-2008, Mark Little, University of Newcastle upon Tyne
+ * and others contributors as indicated 
+ * by the @authors tag. All rights reserved. 
+ * See the copyright.txt in the distribution for a
+ * full listing of individual contributors. 
+ * This copyrighted material is made available to anyone wishing to use,
+ * modify, copy, or redistribute it subject to the terms and conditions
+ * of the GNU Lesser General Public License, v. 2.1.
+ * This program is distributed in the hope that it will be useful, but WITHOUT A 
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A 
+ * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
+ * You should have received a copy of the GNU Lesser General Public License,
+ * v.2.1 along with this distribution; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, 
+ * MA  02110-1301, USA.
+ * 
+ * (C) 1990-2008,
+ */
+
+package org.javasim.tests.streams;
+
+import static org.junit.Assert.fail;
+
+import org.javasim.streams.TriangularStream;
+import org.junit.Test;
+
+public class TriangularStreamUnitTest {
+  @Test
+  public void test() throws Exception {
+    TriangularStream str = new TriangularStream(0, 10, 6);
+
+    try {
+      str.getNumber();
+      str.error();
+    } catch (final Exception ex) {
+      fail();
+    }
+
+    str = new TriangularStream(0, 10, 6, 1000);
+
+    try {
+      str.getNumber();
+    } catch (final Exception ex) {
+      fail();
+    }
+
+    str = new TriangularStream(0, 10, 6, 1000, 772532, 1878892441);
+
+    try {
+      str.getNumber();
+      str.error();
+    } catch (final Exception ex) {
+      fail();
+    }
+  }
+}