/** {@inheritDoc} */
 @Override
 public ConstantDoublesSurface evaluate(
     final ConstantDoublesSurface surface, final double percentage, final String newName) {
   Validate.notNull(surface, "surface");
   final double z = surface.getZValue(0., 0.);
   return ConstantDoublesSurface.from(z * (1 + percentage), newName);
 }
 /** {@inheritDoc} */
 @Override
 public ConstantDoublesSurface evaluate(
     final ConstantDoublesSurface surface, final double percentage) {
   Validate.notNull(surface, "surface");
   return evaluate(surface, percentage, "CONSTANT_MULTIPLIER_" + surface.getName());
 }