code: function(numbers, dimension, opt_factor) {
        var factor = opt_factor || 1e5;
        var d;
  
        var lastNumbers = new Array(dimension);
        for (d = 0; d < dimension; ++d) {
          lastNumbers[d] = 0;
        }
  
        var numbersLength = numbers.length;
        for (var i = 0; i < numbersLength;) {
          for (d = 0; d < dimension; ++d, ++i) {
            var num = numbers[i];
            var delta = num - lastNumbers[d];
            lastNumbers[d] = num;
  
            numbers[i] = delta;
          }
        }
  
        return this.encodeFloats(numbers, factor);
      }
docs: APIMethod: encodeDeltas
  Encode a list of n-dimensional points and return an encoded string
  
  Attention: This function will modify the passed array!
  
  Parameters:
  numbers - {Array.<number>} A list of n-dimensional points.
  dimension - {number} The dimension of the points in the list.
  opt_factor - {number=} The factor by which the numbers will be
  multiplied. The remaining decimal places will get rounded away.
  
  Returns:
  {string} The encoded string.