question: public final double doOperation ( ) { final int index = MathUtils . nextInt ( parameter . getDimension ( ) ) ; final Bounds < Double > bounds = parameter . getBounds ( ) ; final double lower = ( lowerBound == null ? bounds . getLowerLimit ( index ) : Math . max ( bounds . getLowerLimit ( index ) , lowerBound ) ) ; final double upper = ( upperBound == null ? bounds . getUpperLimit ( index ) : Math . min ( bounds . getUpperLimit ( index ) , upperBound ) ) ; final double newValue = ( MathUtils . nextDouble ( ) * ( upper - lower ) ) + lower ; parameter . setParameterValue ( index , newValue ) ; return 0.0 ; }
target:  change the parameter and return the hastings ratio.