On Jan 29, 2011, at 6:38 PM, er...@apache.org wrote:
> Author: erans
> Date: Sat Jan 29 23:38:39 2011
> New Revision: 1065146
>
> URL: http://svn.apache.org/viewvc?rev=1065146&view=rev
> Log:
> MATH-503
> Added sigmoid and generalized logistic functions.
>
> Added:
> commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/Logistic.java
> (with props)
> commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/Sigmoid.java
> (with props)
> commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/function/
> commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/function/LogisticTest.java
> (with props)
> commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/function/SigmoidTest.java
> (with props)
>
> Added:
> commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/Logistic.java
> URL:
> http://svn.apache.org/viewvc/commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/Logistic.java?rev=1065146&view=auto
> ==============================================================================
> ---
> commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/Logistic.java
> (added)
> +++
> commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/Logistic.java
> Sat Jan 29 23:38:39 2011
> @@ -0,0 +1,78 @@
> +/*
> + * 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/Generalised_logistic_function";>
> + * Generalised logistic</a> function.
> + *
> + * @version $Revision$ $Date$
> + * @since 3.0
> + */
> +public class Logistic implements UnivariateRealFunction {
> + /** Lower asymptote. */
> + private final double a;
> + /** Upper asymptote. */
> + private final double k;
> + /** Growth rate. */
> + private final double b;
> + /** Parameter that affects near which asymptote maximum growth occurs. */
> + private final double n;
> + /** Parameter that affects the position of the curve along the ordinate
> axis. */
> + private final double q;
> + /** Abscissa of maximum growth. */
> + private final double m;
> +
> + /**
> + * @param k Upper asymptote.
> + * @param m Abscissa of maximum growth.
> + * @param b Growth rate.
> + * @param q Parameter that affects the position of the curve along the
> + * ordinate axis.
> + * @param a Lower asymptote.
> + * @param n Parameter that affects near which asymptote the maximum
> + * growth occurs.
> + * @throws NotStrictlyPositiveException if {@code n <= 0}.]
Aren't there other constraints on the parameters? Like upper > lower, growth
rate >= 0? Also, why not use meaningful names for the parameters?
Phil
> + */
> + public Logistic(double k,
> + double m,
> + double b,
> + double q,
> + double a,
> + double n) {
> + if (n <= 0) {
> + throw new NotStrictlyPositiveException(n);
> + }
> +
> + this.k = k;
> + this.m = m;
> + this.b = b;
> + this.q = q;
> + this.a = a;
> + this.n = n;
> + }
> +
> + /** {@inheritDoc} */
> + public double value(double x) {
> + return a + (k - a) / FastMath.pow((1 + q * FastMath.exp(b * (m -
> x))), 1 / n);
> + }
> +}
>
> Propchange:
> commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/Logistic.java
> ------------------------------------------------------------------------------
> svn:eol-style = native
>
> Added:
> commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/Sigmoid.java
> URL:
> http://svn.apache.org/viewvc/commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/Sigmoid.java?rev=1065146&view=auto
> ==============================================================================
> ---
> commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/Sigmoid.java
> (added)
> +++
> commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/Sigmoid.java
> Sat Jan 29 23:38:39 2011
> @@ -0,0 +1,38 @@
> +/*
> + * 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/Sigmoid_function";>
> + * Sigmoid</a> function.
> + * A more flexible version, the generalised logistic, is implemented
> + * by the {@link Logistic} class.
> + *
> + * @version $Revision$ $Date$
> + * @since 3.0
> + */
> +public class Sigmoid implements UnivariateRealFunction {
> + /** {@inheritDoc} */
> + public double value(double x) {
> + return 1 / (1 + FastMath.exp(-x));
> + }
> +}
>
> Propchange:
> commons/proper/math/trunk/src/main/java/org/apache/commons/math/analysis/function/Sigmoid.java
> ------------------------------------------------------------------------------
> svn:eol-style = native
>
> Added:
> commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/function/LogisticTest.java
> URL:
> http://svn.apache.org/viewvc/commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/function/LogisticTest.java?rev=1065146&view=auto
> ==============================================================================
> ---
> commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/function/LogisticTest.java
> (added)
> +++
> commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/function/LogisticTest.java
> Sat Jan 29 23:38:39 2011
> @@ -0,0 +1,84 @@
> +/*
> + * 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 Logistic}.
> + */
> +public class LogisticTest {
> + private final double EPS = Math.ulp(1d);
> +
> + @Test
> + public void testPreconditions() {
> + try {
> + final UnivariateRealFunction f = new Logistic(1, 0, 1, 1, 0, -1);
> + } catch (NotStrictlyPositiveException e) {
> + // Expected.
> + }
> +
> + try {
> + final UnivariateRealFunction f = new Logistic(1, 0, 1, 1, 0, 0);
> + } catch (NotStrictlyPositiveException e) {
> + // Expected.
> + }
> + }
> +
> + @Test
> + public void testCompareSigmoid() {
> + final UnivariateRealFunction sig = new Sigmoid();
> + final UnivariateRealFunction sigL = new Logistic(1, 0, 1, 1, 0, 1);
> +
> + final double min = -2;
> + final double max = 2;
> + final int n = 100;
> + final double delta = (max - min) / n;
> + for (int i = 0; i < n; i++) {
> + final double x = min + i * delta;
> + Assert.assertEquals("x=" + x, sig.value(x), sigL.value(x), EPS);
> + }
> + }
> +
> + @Test
> + public void testSomeValues() {
> + final double k = 4;
> + final double m = 5;
> + final double b = 2;
> + final double q = 3;
> + final double a = -1;
> + final double n = 2;
> +
> + final UnivariateRealFunction f = new Logistic(k, m, b, q, a, n);
> +
> + double x;
> + x = m;
> + Assert.assertEquals("x=" + x, a + (k - a) / FastMath.sqrt(1 + q),
> f.value(x), EPS);
> +
> + x = Double.NEGATIVE_INFINITY;
> + Assert.assertEquals("x=" + x, a, f.value(x), EPS);
> +
> + x = Double.POSITIVE_INFINITY;
> + Assert.assertEquals("x=" + x, k, f.value(x), EPS);
> + }
> +}
>
> Propchange:
> commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/function/LogisticTest.java
> ------------------------------------------------------------------------------
> svn:eol-style = native
>
> Added:
> commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/function/SigmoidTest.java
> URL:
> http://svn.apache.org/viewvc/commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/function/SigmoidTest.java?rev=1065146&view=auto
> ==============================================================================
> ---
> commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/function/SigmoidTest.java
> (added)
> +++
> commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/function/SigmoidTest.java
> Sat Jan 29 23:38:39 2011
> @@ -0,0 +1,47 @@
> +/*
> + * 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 Sigmoid}.
> + */
> +public class SigmoidTest {
> + private final double EPS = Math.ulp(1d);
> +
> + @Test
> + public void testSomeValues() {
> + final UnivariateRealFunction f = new Sigmoid();
> +
> + double x;
> + x = 0;
> + Assert.assertEquals("x=" + x, 0.5, f.value(x), EPS);
> +
> + x = Double.NEGATIVE_INFINITY;
> + Assert.assertEquals("x=" + x, 0, f.value(x), EPS);
> +
> + x = Double.POSITIVE_INFINITY;
> + Assert.assertEquals("x=" + x, 1, f.value(x), EPS);
> + }
> +}
>
> Propchange:
> commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/function/SigmoidTest.java
> ------------------------------------------------------------------------------
> svn:eol-style = native
>
>
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