code: private double denseTensorInnerProduct(DenseTensor other) {
      double[] otherValues = other.values;
      int length = values.length;
      Preconditions.checkArgument(otherValues.length == length);
      
      double innerProduct = 0.0;
      for (int i = 0; i < length; i++) {
        innerProduct += values[i] * otherValues[i];
      }
      return innerProduct;
    }
docs: Implementation of inner product where both tensors are dense and have
  the same dimensionality. These properties enable the inner product to
  be computed extremely quickly by iterating over both dense arrays of
  values.
  
  @param other
  @return