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package optimization.stopCriteria;
import optimization.gradientBasedMethods.Objective;
import optimization.gradientBasedMethods.ProjectedObjective;
import optimization.util.MathUtils;
public class ProjectedGradientL2Norm implements StopingCriteria{
/**
* Stop if gradientNorm/(originalGradientNorm) smaller
* than gradientConvergenceValue
*/
protected double gradientConvergenceValue;
public ProjectedGradientL2Norm(double gradientConvergenceValue){
this.gradientConvergenceValue = gradientConvergenceValue;
}
public void reset(){
}
double[] projectGradient(ProjectedObjective obj){
if(obj.auxParameters == null){
obj.auxParameters = new double[obj.getNumParameters()];
}
System.arraycopy(obj.getParameters(), 0, obj.auxParameters, 0, obj.getNumParameters());
MathUtils.minusEquals(obj.auxParameters, obj.gradient, 1);
obj.auxParameters = obj.projectPoint(obj.auxParameters);
MathUtils.minusEquals(obj.auxParameters,obj.getParameters(),1);
return obj.auxParameters;
}
public boolean stopOptimization(Objective obj){
if(obj instanceof ProjectedObjective) {
ProjectedObjective o = (ProjectedObjective) obj;
double norm = MathUtils.L2Norm(projectGradient(o));
if(norm < gradientConvergenceValue){
// System.out.println("Gradient norm below treshold: " + norm);
return true;
}else{
// System.out.println("projected gradient norm: " + norm);
return false;
}
}
System.out.println("Not a projected objective");
throw new RuntimeException();
}
}
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