[PD] tabread4~ "broken" interpolation algorithm - was Re: Max Smoother Audio than Pd?

[Matteo Sisti Sette]

Miller Puckette escribió:

> The tabread4~ algorithm is to put a cubic through the 4 points surrounding
> the input point.  However, this cubic curve does not necessarily match the
> next curve over in first derivative.

Oh I see! I thought it did. I confuded that technique with natural cubic 
splines :$

Now I remember that in order to compute the coefficients for a cspline
you have to know in advance all the points of the table (iirc). But the
general formula for csplines doesn't assume equally spaced points...

So now i dubt is it possible at all to find the piecewise cubic that 
ensures continuity of the 1st and 2nd derivatives by using 4 points at a 
time? (at least in the case of equally spaced points)


thanks
m.


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Matteo Sisti Sette
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