On Wed, 28 Aug 2013 04:53:26 -0700 (PDT), Thomas wrote:
Hi!
I have tried to use the CMAESOptimizer but unfortunately the program
(given
below) is aborted with the following exception:
Exception in thread "main" java.lang.NullPointerException
at
org.apache.commons.math3.optim.nonlinear.scalar.noderiv.CMAESOptimizer.checkParameters(CMAESOptimizer.java:554)
at
org.apache.commons.math3.optim.nonlinear.scalar.noderiv.CMAESOptimizer.parseOptimizationData(CMAESOptimizer.java:542)
at
org.apache.commons.math3.optim.BaseOptimizer.optimize(BaseOptimizer.java:137)
at
org.apache.commons.math3.optim.BaseMultivariateOptimizer.optimize(BaseMultivariateOptimizer.java:66)
at
org.apache.commons.math3.optim.nonlinear.scalar.MultivariateOptimizer.optimize(MultivariateOptimizer.java:64)
at
org.apache.commons.math3.optim.nonlinear.scalar.noderiv.CMAESOptimizer.optimize(CMAESOptimizer.java:363)
at CMA_ES.main(CMA_ES.java:122)
The optimizer I used as follows:
public static void main(String[] args){
MultivariateFunction f = new MultivariateFunction() {
@Override
public double value(double[] arg0) {
double res = 0;
for(int i = 0; i < arg0.length; i++){
res = res + Math.pow(arg0[i], 2);
}
return res;
}
};
int dim = 50;
JDKRandomGenerator rand = new JDKRandomGenerator();
rand.setSeed(1503);
double[] sigma = new double[dim];
for(int i = 0; i < dim; i++){
sigma[i] = 5;
}
SimpleValueChecker checker = new SimpleValueChecker(1E-3, 1E-6);
CMAESOptimizer opt = new CMAESOptimizer(Integer.MAX_VALUE,
Double.NEGATIVE_INFINITY, true, 1, 1, rand, false, checker);
PointValuePair p = opt.optimize(new ObjectiveFunction(f),
GoalType.MINIMIZE, new CMAESOptimizer.Sigma(sigma), new
CMAESOptimizer.PopulationSize(25));
According to the API I have to specify the objective function and the
goal
of optimization. Moreover, if using the CMAES I have also to specify
Sigma
and PopulationSize. Obviously, I specified these parameters in my
code,
hence I wonder a bit why the exception is thrown. Does anyone has
suggestions? Thanks a lot.
The error is a missing "starting point".
See apidocs of the parent class(es).
HTH,
Gilles
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