odeXX interpolation

[Carlo De Falco]

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?

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