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From er...@apache.org
Subject svn commit: r1067917 - in /commons/proper/math/trunk/src: main/java/org/apache/commons/math/analysis/function/ test/java/org/apache/commons/math/analysis/function/
Date Mon, 07 Feb 2011 11:17:43 GMT
Author: erans
Date: Mon Feb  7 11:17:42 2011
New Revision: 1067917

URL: http://svn.apache.org/viewvc?rev=1067917&view=rev
Log:
MATH-503
Added gaussian function.
Added "package.html" doc file.

Added:
    commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/Gaussian.java
  (with props)
    commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/package.html
  (with props)
    commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/function/GaussianTest.java
  (with props)

Added: commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/Gaussian.java
URL: http://svn.apache.org/viewvc/commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/Gaussian.java?rev=1067917&view=auto
==============================================================================
--- commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/Gaussian.java
(added)
+++ commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/Gaussian.java
Mon Feb  7 11:17:42 2011
@@ -0,0 +1,83 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.commons.math.analysis.function;
+
+import org.apache.commons.math.analysis.UnivariateRealFunction;
+import org.apache.commons.math.exception.NotStrictlyPositiveException;
+import org.apache.commons.math.util.FastMath;
+
+/**
+ * <a href="http://en.wikipedia.org/wiki/Gaussian_function">
+ *  Gaussian</a> function.
+ *
+ * @version $Revision$ $Date$
+ * @since 3.0
+ */
+public class Gaussian implements UnivariateRealFunction {
+    /** Mean. */
+    private final double mean;
+    /** Inverse of twice the square of the standard deviation. */
+    private final double i2s2;
+    /** Normalization factor. */
+    private final double norm;
+
+    /**
+     * Gaussian with given normalization factor, mean and standard deviation.
+     *
+     * @param norm Normalization factor.
+     * @param mean Mean.
+     * @param sigma Standard deviation.
+     * @throws NotStrictlyPositiveException if {@code sigma <= 0}.
+     */
+    public Gaussian(double norm,
+                    double mean,
+                    double sigma) {
+        if (sigma <= 0) {
+            throw new NotStrictlyPositiveException(sigma);
+        }
+
+        this.norm = norm;
+        this.mean = mean;
+        this.i2s2 = 1 / (2 * sigma * sigma);
+    }
+
+    /**
+     * Normalized gaussian with given mean and standard deviation.
+     *
+     * @param mean Mean.
+     * @param sigma Standard deviation.
+     * @throws NotStrictlyPositiveException if {@code sigma <= 0}.
+     */
+    public Gaussian(double mean,
+                    double sigma) {
+        this(1 / (sigma * FastMath.sqrt(2 * Math.PI)), mean, sigma);
+    }
+
+    /**
+     * Normalized gaussian with zero mean and unit standard deviation.
+     */
+    public Gaussian() {
+        this(0, 1);
+    }
+
+    /** {@inheritDoc} */
+    public double value(double x) {
+        final double diff = x - mean;
+        return norm * FastMath.exp(-diff * diff * i2s2);
+    }
+}

Propchange: commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/Gaussian.java
------------------------------------------------------------------------------
    svn:eol-style = native

Added: commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/package.html
URL: http://svn.apache.org/viewvc/commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/package.html?rev=1067917&view=auto
==============================================================================
--- commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/package.html
(added)
+++ commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/package.html
Mon Feb  7 11:17:42 2011
@@ -0,0 +1,26 @@
+<html>
+<!--
+   Licensed to the Apache Software Foundation (ASF) under one or more
+  contributor license agreements.  See the NOTICE file distributed with
+  this work for additional information regarding copyright ownership.
+  The ASF licenses this file to You under the Apache License, Version 2.0
+  (the "License"); you may not use this file except in compliance with
+  the License.  You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+  -->
+    <!-- $Revision$ $Date$ -->
+  <body>
+    <p>
+      The {@code function} package contains function objects that wrap the
+      methods contained in {@link java.lang.Math}, as well as common
+      mathematical functions such as the gaussian and sinc functions.
+    </p>
+  </body>
+</html>

Propchange: commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/package.html
------------------------------------------------------------------------------
    svn:eol-style = native

Added: commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/function/GaussianTest.java
URL: http://svn.apache.org/viewvc/commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/function/GaussianTest.java?rev=1067917&view=auto
==============================================================================
--- commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/function/GaussianTest.java
(added)
+++ commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/function/GaussianTest.java
Mon Feb  7 11:17:42 2011
@@ -0,0 +1,46 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.commons.math.analysis.function;
+
+import org.apache.commons.math.analysis.UnivariateRealFunction;
+import org.apache.commons.math.exception.NotStrictlyPositiveException;
+import org.apache.commons.math.util.FastMath;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * Test for class {@link Gaussian}.
+ */
+public class GaussianTest {
+    private final double EPS = Math.ulp(1d);
+
+    @Test(expected=NotStrictlyPositiveException.class)
+    public void testPreconditions() {
+        new Gaussian(1, 2, -1);
+    }
+
+    @Test
+    public void testSomeValues() {
+        final UnivariateRealFunction f = new Gaussian();
+
+        Assert.assertEquals(0, f.value(Double.NEGATIVE_INFINITY), 0);
+        Assert.assertEquals(1 / FastMath.sqrt(2 * Math.PI), f.value(0), EPS);
+        Assert.assertEquals(0, f.value(Double.POSITIVE_INFINITY), 0);
+    }
+}

Propchange: commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/function/GaussianTest.java
------------------------------------------------------------------------------
    svn:eol-style = native



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