In [2] the authors have asserted that their proposed partially blended rational bi-cubic spline is shapepreserving only for monotone and convex data. In this paper, we prove that the scheme of [2] also positive shape preserving interpolation for positive data. We begin with positive interpolating for curve. Then the sufficient condition for positive surfaceinterpolation is derived on all four boundary curves to form positive interpolating surface. Several numerical results are presented including comparison with some existing scheme.
