Yes, as far as I know it's identical -- when you do one of these interpolations with four points, you can either think of it in terms of a cubic polynomial formula involving those four points, or in terms of the sum of four scaled "basis functions" - the latter seems to me intuitively equivalent to direct convolution of an impulse response centered on the four points, and scaled to each. It will be limited by the quantization of the index, so in that sense it might not be linear..
MB
On Tue, Mar 30, 2010 at 6:45 AM, Matteo Sisti Sette matteosistisette@gmail.com wrote:
Is it really possible to express a cubic interpolator (such as Lagrange or Hermite, i.e. such as tabread4 or tabread4c) in terms of impulse response? Is it equivalent to a convolution? That is to ask: is it linear??? Or is that an approximation?
-- Matteo Sisti Sette matteosistisette@gmail.com http://www.matteosistisette.com