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https://issues.apache.org/jira/browse/MATH-303?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Phil Steitz closed MATH-303.
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> CurveFitter.fit(ParametricRealFunction, double[]) used with
> LevenbergMarquardtOptimizer throws ArrayIndexOutOfBoundsException when
> double[] length > 1 (AbstractLeastSquaresOptimizer.java:187)
> -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: MATH-303
> URL: https://issues.apache.org/jira/browse/MATH-303
> Project: Commons Math
> Issue Type: Bug
> Affects Versions: 2.0
> Environment: Java, Linux Ubuntu 9.04 (64 bit)
> Reporter: Daren Drummond
> Fix For: 2.1
>
>
> CurveFitter.fit(ParametricRealFunction, double[]) throws
> ArrayIndexOutOfBoundsException at AbstractLeastSquaresOptimizer.java:187 when
> used with the LevenbergMarquardtOptimizer and the length of the initial
> guess array is greater than 1. The code will run if the initialGuess array
> is of length 1, but then CurveFitter.fit() just returns the same value as the
> initialGuess array (I'll file this as a separate issue). Here is my example
> code:
> {code:title=CurveFitter with LevenbergMarquardtOptimizer and
> SimpleInverseFunction|borderStyle=solid}
> LevenbergMarquardtOptimizer optimizer = new LevenbergMarquardtOptimizer();
> CurveFitter fitter = new CurveFitter(optimizer);
> fitter.addObservedPoint(2.805d, 0.6934785852953367d);
> fitter.addObservedPoint(2.74333333333333d, 0.6306772025518496d);
> fitter.addObservedPoint(1.655d, 0.9474675497289684);
> fitter.addObservedPoint(1.725d, 0.9013594835804194d);
> SimpleInverseFunction sif = new SimpleInverseFunction(); // Class provided
> below
> double[] initialguess = new double[2];
> initialguess[0] = 1.0d;
> initialguess[1] = .5d;
> double[] bestCoefficients = fitter.fit(sif, initialguess); // <---- throws
> exception here
> /**
> * This is my implementation of ParametricRealFunction
> * Implements y = ax^-1 + b for use with an Apache CurveFitter
> implementation
> */
> private class SimpleInverseFunction implements ParametricRealFunction
> {
> public double value(double x, double[] doubles) throws
> FunctionEvaluationException
> {
> //y = ax^-1 + b
> //"double[] must include at least 1 but not more than 2
> coefficients."
> if(doubles == null || doubles.length ==0 || doubles.length > 2)
> throw new FunctionEvaluationException(doubles);
> double a = doubles[0];
> double b = 0;
> if(doubles.length >= 2) b = doubles[1];
> return a * Math.pow(x, -1d) + b;
> }
> public double[] gradient(double x, double[] doubles) throws
> FunctionEvaluationException
> {
> //derivative: -ax^-2
> //"double[] must include at least 1 but not more than 2
> coefficients."
> if(doubles == null || doubles.length ==0 || doubles.length > 2)
> throw new FunctionEvaluationException(doubles);
> double a = doubles[0];
> double b = 0;
> if(doubles.length >= 2) b = doubles[1];
> double derivative = -a * Math.pow(x, -2d);
> double[]gradientVector = new double[1];
> gradientVector[0] = derivative;
> return gradientVector;
> }
> }
> {code}
> This is the resulting stack trace:
> java.lang.ArrayIndexOutOfBoundsException: 1
> at
> org.apache.commons.math.optimization.general.AbstractLeastSquaresOptimizer.updateJacobian(AbstractLeastSquaresOptimizer.java:187)
> at
> org.apache.commons.math.optimization.general.LevenbergMarquardtOptimizer.doOptimize(LevenbergMarquardtOptimizer.java:241)
> at
> org.apache.commons.math.optimization.general.AbstractLeastSquaresOptimizer.optimize(AbstractLeastSquaresOptimizer.java:346)
> at
> org.apache.commons.math.optimization.fitting.CurveFitter.fit(CurveFitter.java:134)
> at
> com.yieldsoftware.analyticstest.tasks.ppcbidder.CurveFittingTest.testFitnessRankCurveIntercept(CurveFittingTest.java:181)
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