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Posted to dev@commons.apache.org by Luc Maisonobe <Lu...@free.fr> on 2010/07/26 20:17:54 UTC
Re: svn commit: r979257 - in /commons/proper/math/trunk/src: main/java/org/apache/commons/math/optimization/univariate/
site/xdoc/ test/java/org/apache/commons/math/analysis/ test/java/org/apache/commons/math/optimization/
test/java/org/apache/commons/math...
Le 26/07/2010 14:17, erans@apache.org a écrit :
> Author: erans
> Date: Mon Jul 26 12:17:45 2010
> New Revision: 979257
>
> URL: http://svn.apache.org/viewvc?rev=979257&view=rev
> Log:
> Fixed bugs in "BrentOptimizer".
> Renamed "BrentMinimizerTest" to "BrentOptimizerTest".
> Modified "MultiStartUnivariateRealOptimizerTest" because it uses
> "BrentOptimizer" as the underlying optimizer, and so was affected
> by the changes.
>
> Added:
> commons/proper/math/trunk/src/test/java/org/apache/commons/math/optimization/univariate/BrentOptimizerTest.java (with props)
> Removed:
> commons/proper/math/trunk/src/test/java/org/apache/commons/math/optimization/univariate/BrentMinimizerTest.java
> Modified:
> commons/proper/math/trunk/src/main/java/org/apache/commons/math/optimization/univariate/BrentOptimizer.java
> commons/proper/math/trunk/src/site/xdoc/changes.xml
> commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/QuinticFunction.java
> commons/proper/math/trunk/src/test/java/org/apache/commons/math/optimization/MultiStartUnivariateRealOptimizerTest.java
>
> Modified: commons/proper/math/trunk/src/main/java/org/apache/commons/math/optimization/univariate/BrentOptimizer.java
> URL: http://svn.apache.org/viewvc/commons/proper/math/trunk/src/main/java/org/apache/commons/math/optimization/univariate/BrentOptimizer.java?rev=979257&r1=979256&r2=979257&view=diff
> ==============================================================================
> --- commons/proper/math/trunk/src/main/java/org/apache/commons/math/optimization/univariate/BrentOptimizer.java (original)
> +++ commons/proper/math/trunk/src/main/java/org/apache/commons/math/optimization/univariate/BrentOptimizer.java Mon Jul 26 12:17:45 2010
> @@ -18,19 +18,20 @@ package org.apache.commons.math.optimiza
>
> import org.apache.commons.math.FunctionEvaluationException;
> import org.apache.commons.math.MaxIterationsExceededException;
> +import org.apache.commons.math.exception.NotStrictlyPositiveException;
> import org.apache.commons.math.analysis.UnivariateRealFunction;
> import org.apache.commons.math.optimization.GoalType;
>
> /**
> * Implements Richard Brent's algorithm (from his book "Algorithms for
> * Minimization without Derivatives", p. 79) for finding minima of real
> - * univariate functions.
> + * univariate functions. This implementation is an adaptation partly
> + * based on the Python code from SciPy (module "optimize.py" v0.5).
If the implementation is partly based on SciPy, there must be a
reference to it in the NOTICE file. It is *really* important to be very
careful about the origin of our code and to check the license terms.
Fortunately, SciPy license is published under the terms of the BSD
license, which is compatible with Apache Software License.
Luc
> *
> * @version $Revision$ $Date$
> * @since 2.0
> */
> public class BrentOptimizer extends AbstractUnivariateRealOptimizer {
> -
> /**
> * Golden section.
> */
> @@ -47,15 +48,16 @@ public class BrentOptimizer extends Abst
> public double optimize(final UnivariateRealFunction f, final GoalType goalType,
> final double min, final double max, final double startValue)
> throws MaxIterationsExceededException, FunctionEvaluationException {
> - return optimize(f, goalType, min, max);
> + clearResult();
> + return localMin(f, goalType, min, startValue, max,
> + getRelativeAccuracy(), getAbsoluteAccuracy());
> }
>
> /** {@inheritDoc} */
> public double optimize(final UnivariateRealFunction f, final GoalType goalType,
> final double min, final double max)
> throws MaxIterationsExceededException, FunctionEvaluationException {
> - clearResult();
> - return localMin(f, goalType, min, max, relativeAccuracy, absoluteAccuracy);
> + return optimize(f, goalType, min, max, min + GOLDEN_SECTION * (max - min));
> }
>
> /**
> @@ -69,23 +71,41 @@ public class BrentOptimizer extends Abst
> * {@code eps} should be no smaller than <em>2 macheps</em> and preferable not
> * much less than <em>sqrt(macheps)</em>, where <em>macheps</em> is the relative
> * machine precision. {@code t} should be positive.
> - * @param f the function to solve
> + * @param f the function to solve.
> * @param goalType type of optimization goal: either {@link GoalType#MAXIMIZE}
> - * or {@link GoalType#MINIMIZE}
> - * @param a Lower bound of the interval
> - * @param b Higher bound of the interval
> - * @param eps Relative accuracy
> - * @param t Absolute accuracy
> - * @return the point at which the function is minimal.
> + * or {@link GoalType#MINIMIZE}.
> + * @param lo Lower bound of the interval.
> + * @param mid Point inside the interval {@code [lo, hi]}.
> + * @param hi Higher bound of the interval.
> + * @param eps Relative accuracy.
> + * @param t Absolute accuracy.
> + * @return the optimum point.
> * @throws MaxIterationsExceededException if the maximum iteration count
> * is exceeded.
> * @throws FunctionEvaluationException if an error occurs evaluating
> * the function.
> */
> - private double localMin(final UnivariateRealFunction f, final GoalType goalType,
> - double a, double b, final double eps, final double t)
> + private double localMin(UnivariateRealFunction f,
> + GoalType goalType,
> + double lo, double mid, double hi,
> + double eps, double t)
> throws MaxIterationsExceededException, FunctionEvaluationException {
> - double x = a + GOLDEN_SECTION * (b - a);
> + if (eps <= 0) {
> + throw new NotStrictlyPositiveException(eps);
> + }
> + if (t <= 0) {
> + throw new NotStrictlyPositiveException(t);
> + }
> + double a, b;
> + if (lo < hi) {
> + a = lo;
> + b = hi;
> + } else {
> + a = hi;
> + b = lo;
> + }
> +
> + double x = mid;
> double v = x;
> double w = x;
> double e = 0;
> @@ -99,18 +119,18 @@ public class BrentOptimizer extends Abst
> int count = 0;
> while (count < maximalIterationCount) {
> double m = 0.5 * (a + b);
> - double tol = eps * Math.abs(x) + t;
> - double t2 = 2 * tol;
> + final double tol1 = eps * Math.abs(x) + t;
> + final double tol2 = 2 * tol1;
>
> // Check stopping criterion.
> - if (Math.abs(x - m) > t2 - 0.5 * (b - a)) {
> + if (Math.abs(x - m) > tol2 - 0.5 * (b - a)) {
> double p = 0;
> double q = 0;
> double r = 0;
> double d = 0;
> double u = 0;
>
> - if (Math.abs(e) > tol) { // Fit parabola.
> + if (Math.abs(e) > tol1) { // Fit parabola.
> r = (x - w) * (fx - fv);
> q = (x - v) * (fx - fw);
> p = (x - v) * q - (x - w) * r;
> @@ -124,24 +144,53 @@ public class BrentOptimizer extends Abst
>
> r = e;
> e = d;
> - }
> -
> - if (Math.abs(p) < Math.abs(0.5 * q * r) &&
> - (p < q * (a - x)) && (p < q * (b - x))) { // Parabolic interpolation step.
> - d = p / q;
> - u = x + d;
>
> - // f must not be evaluated too close to a or b.
> - if (((u - a) < t2) || ((b - u) < t2)) {
> - d = (x < m) ? tol : -tol;
> + if (p > q * (a - x)
> + && p < q * (b - x)
> + && Math.abs(p) < Math.abs(0.5 * q * r)) {
> + // Parabolic interpolation step.
> + d = p / q;
> + u = x + d;
> +
> + // f must not be evaluated too close to a or b.
> + if (u - a < tol2
> + || b - u < tol2) {
> + if (x <= m) {
> + d = tol1;
> + } else {
> + d = -tol1;
> + }
> + }
> + } else {
> + // Golden section step.
> + if (x < m) {
> + e = b - x;
> + } else {
> + e = a - x;
> + }
> + d = GOLDEN_SECTION * e;
> + }
> + } else {
> + // Golden section step.
> + if (x < m) {
> + e = b - x;
> + } else {
> + e = a - x;
> }
> - } else { // Golden section step.
> - e = ((x < m) ? b : a) - x;
> d = GOLDEN_SECTION * e;
> }
>
> - // f must not be evaluated too close to a or b.
> - u = x + ((Math.abs(d) > tol) ? d : ((d > 0) ? tol : -tol));
> + // Update by at least "tol1".
> + if (Math.abs(d) < tol1) {
> + if (d >= 0) {
> + u = x + tol1;
> + } else {
> + u = x - tol1;
> + }
> + } else {
> + u = x + d;
> + }
> +
> double fu = computeObjectiveValue(f, u);
> if (goalType == GoalType.MAXIMIZE) {
> fu = -fu;
> @@ -166,12 +215,15 @@ public class BrentOptimizer extends Abst
> } else {
> b = u;
> }
> - if ((fu <= fw) || (w == x)) {
> + if (fu <= fw
> + || w == x) {
> v = w;
> fv = fw;
> w = u;
> fw = fu;
> - } else if ((fu <= fv) || (v == x) || (v == w)) {
> + } else if (fu <= fv
> + || v == x
> + || v == w) {
> v = u;
> fv = fu;
> }
> @@ -180,12 +232,8 @@ public class BrentOptimizer extends Abst
> setResult(x, (goalType == GoalType.MAXIMIZE) ? -fx : fx, count);
> return x;
> }
> -
> ++count;
> }
> -
> throw new MaxIterationsExceededException(maximalIterationCount);
> -
> }
> -
> }
>
> Modified: commons/proper/math/trunk/src/site/xdoc/changes.xml
> URL: http://svn.apache.org/viewvc/commons/proper/math/trunk/src/site/xdoc/changes.xml?rev=979257&r1=979256&r2=979257&view=diff
> ==============================================================================
> --- commons/proper/math/trunk/src/site/xdoc/changes.xml (original)
> +++ commons/proper/math/trunk/src/site/xdoc/changes.xml Mon Jul 26 12:17:45 2010
> @@ -52,6 +52,9 @@ The <action> type attribute can be add,u
> If the output is not quite correct, check for invisible trailing spaces!
> -->
> <release version="2.2" date="TBD" description="TBD">
> + <action dev="erans" type="fix" issue="MATH-395">
> + Fixed several bugs in "BrentOptimizer".
> + </action>
> <action dev="erans" type="fix" issue="MATH-393">
> Fixed inconsistency in return values in "MultiStartUnivariateRealOptimizer".
> </action>
>
> Modified: commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/QuinticFunction.java
> URL: http://svn.apache.org/viewvc/commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/QuinticFunction.java?rev=979257&r1=979256&r2=979257&view=diff
> ==============================================================================
> --- commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/QuinticFunction.java (original)
> +++ commons/proper/math/trunk/src/test/java/org/apache/commons/math/analysis/QuinticFunction.java Mon Jul 26 12:17:45 2010
> @@ -19,7 +19,7 @@ package org.apache.commons.math.analysis
> import org.apache.commons.math.FunctionEvaluationException;
>
> /**
> - * Auxillary class for testing solvers.
> + * Auxiliary class for testing solvers.
> *
> * @version $Revision$ $Date$
> */
>
> Modified: commons/proper/math/trunk/src/test/java/org/apache/commons/math/optimization/MultiStartUnivariateRealOptimizerTest.java
> URL: http://svn.apache.org/viewvc/commons/proper/math/trunk/src/test/java/org/apache/commons/math/optimization/MultiStartUnivariateRealOptimizerTest.java?rev=979257&r1=979256&r2=979257&view=diff
> ==============================================================================
> --- commons/proper/math/trunk/src/test/java/org/apache/commons/math/optimization/MultiStartUnivariateRealOptimizerTest.java (original)
> +++ commons/proper/math/trunk/src/test/java/org/apache/commons/math/optimization/MultiStartUnivariateRealOptimizerTest.java Mon Jul 26 12:17:45 2010
> @@ -48,8 +48,8 @@ public class MultiStartUnivariateRealOpt
> assertEquals(-1.0, f.value(optima[i]), 1.0e-10);
> assertEquals(f.value(optima[i]), optimaValues[i], 1.0e-10);
> }
> - assertTrue(minimizer.getEvaluations() > 2900);
> - assertTrue(minimizer.getEvaluations() < 3100);
> + assertTrue(minimizer.getEvaluations() > 1500);
> + assertTrue(minimizer.getEvaluations() < 1700);
> }
>
> @Test
> @@ -58,8 +58,9 @@ public class MultiStartUnivariateRealOpt
> // The function has extrema (first derivative is zero) at 0.27195613 and 0.82221643,
> UnivariateRealFunction f = new QuinticFunction();
> UnivariateRealOptimizer underlying = new BrentOptimizer();
> + underlying.setRelativeAccuracy(1e-15);
> JDKRandomGenerator g = new JDKRandomGenerator();
> - g.setSeed(4312000053l);
> + g.setSeed(4312000053L);
> MultiStartUnivariateRealOptimizer minimizer =
> new MultiStartUnivariateRealOptimizer(underlying, 5, g);
> minimizer.setAbsoluteAccuracy(10 * minimizer.getAbsoluteAccuracy());
> @@ -82,9 +83,10 @@ public class MultiStartUnivariateRealOpt
> fail("wrong exception caught");
> }
>
> - assertEquals(-0.27195612846834, minimizer.optimize(f, GoalType.MINIMIZE, -0.3, -0.2), 1.0e-13);
> - assertEquals(-0.27195612846834, minimizer.getResult(), 1.0e-13);
> - assertEquals(-0.04433426954946, minimizer.getFunctionValue(), 1.0e-13);
> + double result = minimizer.optimize(f, GoalType.MINIMIZE, -0.3, -0.2);
> + assertEquals(-0.27195612525275803, result, 1.0e-13);
> + assertEquals(-0.27195612525275803, minimizer.getResult(), 1.0e-13);
> + assertEquals(-0.04433426954946637, minimizer.getFunctionValue(), 1.0e-13);
>
> double[] optima = minimizer.getOptima();
> double[] optimaValues = minimizer.getOptimaValues();
> @@ -92,11 +94,9 @@ public class MultiStartUnivariateRealOpt
> assertEquals(f.value(optima[i]), optimaValues[i], 1.0e-10);
> }
>
> - assertTrue(minimizer.getEvaluations() >= 510);
> - assertTrue(minimizer.getEvaluations() <= 530);
> - assertTrue(minimizer.getIterationCount() >= 150);
> - assertTrue(minimizer.getIterationCount() <= 170);
> -
> + assertTrue(minimizer.getEvaluations() >= 300);
> + assertTrue(minimizer.getEvaluations() <= 420);
> + assertTrue(minimizer.getIterationCount() >= 100);
> + assertTrue(minimizer.getIterationCount() <= 140);
> }
> -
> }
>
> Added: commons/proper/math/trunk/src/test/java/org/apache/commons/math/optimization/univariate/BrentOptimizerTest.java
> URL: http://svn.apache.org/viewvc/commons/proper/math/trunk/src/test/java/org/apache/commons/math/optimization/univariate/BrentOptimizerTest.java?rev=979257&view=auto
> ==============================================================================
> --- commons/proper/math/trunk/src/test/java/org/apache/commons/math/optimization/univariate/BrentOptimizerTest.java (added)
> +++ commons/proper/math/trunk/src/test/java/org/apache/commons/math/optimization/univariate/BrentOptimizerTest.java Mon Jul 26 12:17:45 2010
> @@ -0,0 +1,146 @@
> +/*
> + * 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.optimization.univariate;
> +
> +import static org.junit.Assert.assertEquals;
> +import static org.junit.Assert.assertTrue;
> +import static org.junit.Assert.fail;
> +
> +import org.apache.commons.math.FunctionEvaluationException;
> +import org.apache.commons.math.MathException;
> +import org.apache.commons.math.MaxIterationsExceededException;
> +import org.apache.commons.math.analysis.QuinticFunction;
> +import org.apache.commons.math.analysis.SinFunction;
> +import org.apache.commons.math.analysis.SincFunction;
> +import org.apache.commons.math.analysis.UnivariateRealFunction;
> +import org.apache.commons.math.optimization.GoalType;
> +import org.apache.commons.math.optimization.UnivariateRealOptimizer;
> +import org.junit.Test;
> +
> +/**
> + * @version $Revision: 811685 $ $Date: 2009-09-05 19:36:48 +0200 (Sat, 05 Sep 2009) $
> + */
> +public final class BrentOptimizerTest {
> +
> + @Test
> + public void testSinMin() throws MathException {
> + UnivariateRealFunction f = new SinFunction();
> + UnivariateRealOptimizer minimizer = new BrentOptimizer();
> + minimizer.setMaxEvaluations(200);
> + assertEquals(200, minimizer.getMaxEvaluations());
> + try {
> + minimizer.getResult();
> + fail("an exception should have been thrown");
> + } catch (IllegalStateException ise) {
> + // expected
> + } catch (Exception e) {
> + fail("wrong exception caught");
> + }
> + assertEquals(3 * Math.PI / 2, minimizer.optimize(f, GoalType.MINIMIZE, 4, 5), 70 * minimizer.getAbsoluteAccuracy());
> + assertTrue(minimizer.getIterationCount() <= 50);
> + assertEquals(3 * Math.PI / 2, minimizer.optimize(f, GoalType.MINIMIZE, 1, 5), 70 * minimizer.getAbsoluteAccuracy());
> + assertTrue(minimizer.getIterationCount() <= 50);
> + assertTrue(minimizer.getEvaluations() <= 100);
> + assertTrue(minimizer.getEvaluations() >= 30);
> + minimizer.setMaxEvaluations(50);
> + try {
> + minimizer.optimize(f, GoalType.MINIMIZE, 4, 5);
> + fail("an exception should have been thrown");
> + } catch (FunctionEvaluationException fee) {
> + // expected
> + } catch (Exception e) {
> + fail("wrong exception caught");
> + }
> + }
> +
> + @Test
> + public void testQuinticMin() throws MathException {
> + // The function has local minima at -0.27195613 and 0.82221643.
> + UnivariateRealFunction f = new QuinticFunction();
> + UnivariateRealOptimizer minimizer = new BrentOptimizer();
> + assertEquals(-0.27195613, minimizer.optimize(f, GoalType.MINIMIZE, -0.3, -0.2), 1.0e-8);
> + assertEquals( 0.82221643, minimizer.optimize(f, GoalType.MINIMIZE, 0.3, 0.9), 1.0e-8);
> + assertTrue(minimizer.getIterationCount() <= 50);
> +
> + // search in a large interval
> + assertEquals(-0.27195613, minimizer.optimize(f, GoalType.MINIMIZE, -1.0, 0.2), 1.0e-8);
> + assertTrue(minimizer.getIterationCount() <= 50);
> + }
> +
> + @Test
> + public void testQuinticMinPythonComparison() throws MathException {
> + // The function has local minima at -0.27195613 and 0.82221643.
> + UnivariateRealFunction f = new QuinticFunction();
> + UnivariateRealOptimizer minimizer = new BrentOptimizer();
> + minimizer.setRelativeAccuracy(1e-12);
> + minimizer.setAbsoluteAccuracy(1e-11);
> +
> + double result;
> + int nIter, nEval;
> +
> + result = minimizer.optimize(f, GoalType.MINIMIZE, -0.3, -0.2, -0.25);
> + nIter = minimizer.getIterationCount();
> + nEval = minimizer.getEvaluations();
> + // XXX Python: -0.27195612805911351 (instead of -0.2719561279558559).
> + assertEquals(-0.2719561279558559, result, 1e-12);
> + // XXX Python: 15 (instead of 18).
> + assertEquals(18, nEval);
> + // XXX Python: 11 (instead of 17).
> + assertEquals(17, nIter);
> +
> + result = minimizer.optimize(f, GoalType.MINIMIZE, 0.7, 0.9, 0.8);
> + nIter = minimizer.getIterationCount();
> + nEval = minimizer.getEvaluations();
> + // XXX Python: 0.82221643488363705 (instead of 0.8222164326561908).
> + assertEquals(0.8222164326561908, result, 1e-12);
> + // XXX Python: 25 (instead of 43).
> + assertEquals(43, nEval);
> + // XXX Python: 21 (instead of 24).
> + assertEquals(24, nIter);
> + }
> +
> + @Test
> + public void testQuinticMax() throws MathException {
> + // The quintic function has zeros at 0, +-0.5 and +-1.
> + // The function has a local maximum at 0.27195613.
> + UnivariateRealFunction f = new QuinticFunction();
> + UnivariateRealOptimizer minimizer = new BrentOptimizer();
> + assertEquals(0.27195613, minimizer.optimize(f, GoalType.MAXIMIZE, 0.2, 0.3), 1.0e-8);
> + minimizer.setMaximalIterationCount(20);
> + try {
> + minimizer.optimize(f, GoalType.MAXIMIZE, 0.2, 0.3);
> + fail("an exception should have been thrown");
> + } catch (MaxIterationsExceededException miee) {
> + // expected
> + } catch (Exception e) {
> + fail("wrong exception caught");
> + }
> + }
> +
> + @Test
> + public void testMinEndpoints() throws Exception {
> + UnivariateRealFunction f = new SinFunction();
> + UnivariateRealOptimizer solver = new BrentOptimizer();
> +
> + // endpoint is minimum
> + double result = solver.optimize(f, GoalType.MINIMIZE, 3 * Math.PI / 2, 5);
> + assertEquals(3 * Math.PI / 2, result, 70 * solver.getAbsoluteAccuracy());
> +
> + result = solver.optimize(f, GoalType.MINIMIZE, 4, 3 * Math.PI / 2);
> + assertEquals(3 * Math.PI / 2, result, 80 * solver.getAbsoluteAccuracy());
> + }
> +}
>
> Propchange: commons/proper/math/trunk/src/test/java/org/apache/commons/math/optimization/univariate/BrentOptimizerTest.java
> ------------------------------------------------------------------------------
> svn:eol-style = native
>
>
>
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Re: svn commit: r979257 - in /commons/proper/math/trunk/src: main/java/org/apache/commons/math/optimization/univariate/
site/xdoc/ test/java/org/apache/commons/math/analysis/ test/java/org/apache/commons/math/optimization/
test/java/org/apache/commons/math...
Posted by Luc Maisonobe <Lu...@free.fr>.
Le 26/07/2010 22:38, Gilles Sadowski a écrit :
>>> * Implements Richard Brent's algorithm (from his book "Algorithms for
>>> * Minimization without Derivatives", p. 79) for finding minima of real
>>> - * univariate functions.
>>> + * univariate functions. This implementation is an adaptation partly
>>> + * based on the Python code from SciPy (module "optimize.py" v0.5).
>>
>> If the implementation is partly based on SciPy, there must be a
>> reference to it in the NOTICE file. It is *really* important to be very
>> careful about the origin of our code and to check the license terms.
>> Fortunately, SciPy license is published under the terms of the BSD
>> license, which is compatible with Apache Software License.
>
> The Python implementation is no more original than the Java one as it is
> obviously similarly based on the algorithm description in Brent's book. Its
> main advantage is that it works whereas my original translation (introduced
> in 2.0) contained several bugs. The notice in the Javadoc was to acknowledge
> that I used the Python implementation in order to figure out where the
> mistakes were in my implementation.
Fine. I thought the version from 2.0 was already derived from this. Now
I remember you already told me it was from the original algorithm, sorry
for that.
>
> Now, for Powell's algorithm, which I'm going to introduce in CM (MATH-396),
> the Python code is really the only reference; thus I'll indicate it in the
> "NOTICE.txt" file.
Thanks
Luc
>
>
> Gilles
>
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Re: svn commit: r979257 - in /commons/proper/math/trunk/src:
main/java/org/apache/commons/math/optimization/univariate/ site/xdoc/
test/java/org/apache/commons/math/analysis/
test/java/org/apache/commons/math/optimization/
test/java/org/apache/commons/math...
Posted by Gilles Sadowski <gi...@harfang.homelinux.org>.
> > * Implements Richard Brent's algorithm (from his book "Algorithms for
> > * Minimization without Derivatives", p. 79) for finding minima of real
> > - * univariate functions.
> > + * univariate functions. This implementation is an adaptation partly
> > + * based on the Python code from SciPy (module "optimize.py" v0.5).
>
> If the implementation is partly based on SciPy, there must be a
> reference to it in the NOTICE file. It is *really* important to be very
> careful about the origin of our code and to check the license terms.
> Fortunately, SciPy license is published under the terms of the BSD
> license, which is compatible with Apache Software License.
The Python implementation is no more original than the Java one as it is
obviously similarly based on the algorithm description in Brent's book. Its
main advantage is that it works whereas my original translation (introduced
in 2.0) contained several bugs. The notice in the Javadoc was to acknowledge
that I used the Python implementation in order to figure out where the
mistakes were in my implementation.
Now, for Powell's algorithm, which I'm going to introduce in CM (MATH-396),
the Python code is really the only reference; thus I'll indicate it in the
"NOTICE.txt" file.
Gilles
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