code: @Override
      public double getWithDefault(int idx, double defaultVal) {
  		int i = Arrays.binarySearch(indices, 0, used, idx);
  		if (i < 0) {
  			return defaultVal;
  		}
  		return values[i];
  	}
docs: /* (non-Javadoc)
  @see edu.jhu.util.vector.IntDoubleMap#getWithDefault(int, double)