code: @Override
  	public double integrate(DoubleUnaryOperator integrand) {
  
  		// We use commons-math RombergIntegrator
  		return new RombergIntegrator().integrate(numberOfEvaluationPoints, new UnivariateFunction() {
  			@Override
  			public double value(double argument) {
  				return integrand.applyAsDouble(argument);
  			}
  		}, getLowerBound(), getUpperBound());
  	}
docs: /* (non-Javadoc)
  @see net.finmath.integration.AbstractRealIntegral#integrate(java.util.function.DoubleUnaryOperator)