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Re: odeXX interpolation


From: Jacopo Corno
Subject: Re: odeXX interpolation
Date: Wed, 21 Oct 2015 13:27:05 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0



On 06/10/2015 18:35, Carlo De Falco wrote:
Hi,

While looking at the functions being moved to core to support the
new ode integrators I noticed that in odekg there are re-implementations
of standard 1d interpolation functions.

For example it is obvious that "linear_interpolation" [0] is equivalent
to interp1 (... , "linear") and therefore it can be removed.

It seems to me that "hermite_cubic_interpolation" [1] is also equivalent
to interp1 (... , "pchip").

Can someone confirm the latter?
Are there other functions for higher order Hermite interpolation in Octave?
Regarding hermite cubic interpolation, I did some tests with interp (..., 'pchip') and the function pchip () itself and they do not allow the interpolation with prescribed derivatives.

This seems to be compliant with Matlab. My suggestion would be to either stay with the hermite_cubic_interpolation function as it is, or, if there is interest to have such a function we could provide it. In File Exchange there seems to exist such a function for Matlab [2].

Jacopo

[2] http://www.mathworks.com/matlabcentral/fileexchange/28944-hermite-cubic-interpolating-polynomial-with-specified-derivatives


c.

[0] 
http://sourceforge.net/p/octave/odepkg/ci/default/tree/inst/dense_output/linear_interpolation.m
[1] 
http://sourceforge.net/p/octave/odepkg/ci/default/tree/inst/dense_output/hermite_cubic_interpolation.m

--

Jacopo Corno M.Sc.
Technische Universität Darmstadt
Graduate School of Computational Engineering
Dolivostraße 15
64293 Darmstadt / Germany

Office: S4|10-232
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