On Sat, 28 Jun 2008, Matt Barber wrote:
It's also bad because while a natural cubic spline is conceivable for a
tabread (fixing the 2nd derivative to zero on both ends, reading in and
keeping all the derived data in a buffer somewhere), you might need a
different kind of spline (periodic?) for a tabosc~
Yes, the periodic version of the natural cubic spline doesn't have 2nd
derivative constraints on endpoints, and instead matches the 1st
derivatives of both ends together. It's a small change in one way, but
it's not in another, because you can't use the shortcuts associated with
tridiagonal matrices.
and it shouldn't work at all for a vd~ since there is no codified
beginning or end to the table (yes-no?).
Right. But actually, it's not really useful to go on about this, it was
just a mistake of mine because I misread a page.
Which is equivalent to the slope between the 2-sample gap. This would
have another advantage over forward- or backward-differences such that
going through the table in reverse would produce a symmetric result.
Yes.
(or actually, would it matter after all, since the four points are in
the same order whether you're going forward or backward through the
table... ?)
This is not the reason, it's because people have more-or-less-defined
expectations about an interpolator, and if one assumes symmetricity
because of a sample that has been flipped backwards and it introduces a
1-delay sample... one got to know... maybe.
_ _ __ ___ _____ ________ _____________ _____________________ ...
| Mathieu Bouchard - tél:+1.514.383.3801, Montréal, Québec
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