[Scilab-users] "Smoothing" very localised discontinuities in curves.

[Rafael Guerra]

Hi Buk.

Have you tried Scilab's cubic splines using the "monotone" option?

Regards,
Rafael

-----Original Message-----
From: users [mailto:users-bounces at lists.scilab.org] On Behalf Of
scilab.20.browseruk at xoxy.net
Sent: Sunday, April 03, 2016 9:09 PM
To: users at lists.scilab.org
Subject: [Scilab-users] "Smoothing" very localised discontinuities in curves.

HI,

The data I'm dealing with is experimentally produced; and thus contains
occasional, localised discontinuities (inflections), that I need to remove
before that data is suitable for is use in FEM modeling software, which requires
that it be strictly monotonic. The attachment shows the full curve plus a close
up of a couple of examples of the type of discontinuity I need to deal with.

I haven't yet decided whether to simply omit points (thus connect A to F & G to
J) or whether to retain the same number of points by interpolating new points
onto that line as shown in red.

I've looked and played several of the smoothing, convolution and interpolation
routines that scilab provides, but (besides that I don't understand the output
some of them produce) they also seem to affect the data more than I would like.
Some seem to introduce a 'phase shift'; others smooth out larger scale bumps in
the curve that need to be retained; and others generate many extra points which
I don't think is helpful, the FEM software is going to do its own interpolations
anyway.


But the bit I'm asking about here is how to detect point A&F and G&J? 

Any thoughts or pointers as to a) the algorithm to use; b) how to implement it
in SciLab?

Cheers, Buk.

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