Re: proposal for new m-file function

[Ben Abbott]

On Mar 22, 2012, at 6:31 AM, Martin Helm wrote:

> Am 22.03.2012 10:43, schrieb Carlo de Falco:
>> 
>> 
>> 2012/3/22 <address@hidden
>> <mailto:address@hidden>>
>> 
>>    Message: 2
>>    Date: Wed, 21 Mar 2012 20:33:01 -0400
>>    From: Ben Abbott <address@hidden <mailto:address@hidden>>
>>    To: octave maintainers mailing list <address@hidden
>>    <mailto:address@hidden>>
>>    Subject: proposal for new m-file function
>>    Message-ID: <address@hidden
>>    <mailto:address@hidden>>
>>    Content-Type: text/plain; charset="us-ascii"
>> 
>>    A user's question about fixed points piecewise-linear fitting led
>>    to the development of a function looks to be a good fit for
>>    Octave's core.
>> 
>> 
>>     https://mailman.cae.wisc.edu/pipermail/help-octave/2012-March/050900.html
>> 
>>    The idea was to fit a piece-wise polynomial to a set of data.
>>    After some discussion between myself and Martin Helm, the attached
>>    ppfit.m was produced. The name was chosen to match the existing
>>    ppval().
>> 
>>    The function provides a least-squares fit of a 1D interpolation
>>    with specified break positions to a set of data.
>> 
>>    Demos and tests are included.
>> 
>>    Any concern about adding this to Octave's core ?
>> 
>>    Ben
>> 
>> 
>> googling for the name 'ppfit' I found this function:
>> 
>> https://www.assembla.com/code/zaxxon_scripts/subversion/nodes/trunk/project/scripts/ppfit.m
>> 
>> which seems to do the same as yours with the additional option of
>> returning a spline with N continuous derivatives
>> Would it be possible to add that option to your code?
>> The license of the linked function looks like BSD so it should be no
>> problem to get the code from there.
>> c.
> Wouldn't it be much cleaner to add that additional fitting options
> (quadratics and higher order splines) to interp1 (without breaking
> matlab compatibility of course)?
> I think that is the place where such functionality should naturally
> live. I could look at it over the weekend and propose a patch for it.

Ok. I'll wait on your changeset.

Is it possible for interp1 to return the available methods and whether the 
underlying interpolants are linear functions ?

Ben