Re: polytrans & polyscale

[Jaroslav Hajek]

On Fri, Apr 10, 2009 at 12:19 PM, Thorsten Meyer <address@hidden> wrote:
> Jaroslav Hajek wrote:
>> hi,
>>
>> I recently added the functions polytrans (p(x) -> p(x+a)) and
>> polyscale (p(x) -> p(x*a)) to the scripts/polynomial, though they are
>> not yet added to the build process. Does anyone object to adding these
>> functions definitely? These are not in Matlab core, but then neither
>> is a number of other polynomial functions (polyint, polyout...).
>> Opinons wanted.
>>
> I like those functions. So I vote for adding them to octave.
>
> Still, I have a few remarks:
>  - there seems to be a bug in polytrans: try the example given in the help 
> text.
> It looks as if polytrans calculates f(-x - a)
>  - polyval also contains an option to translate and scale. And it seems to me
> that it will translate into the other direction and scale with the inverse
> compare to polytrans and polyscale. Wouldn't it be better to make those
> functions consistent to avoid confusion?
>  - I notice that there are no tests included in the functions. Also, there is 
> no
> reference to polyval and polytrans in the manual yet. And the doc strings have
> not been fully translated to texinfo. Don't we have the general rule, that
> tests, manual entry and style compliance are required before adding a new 
> function?
>

I addressed these points partly by merging polytrans & polyscale to
"polyaffine" (which someone suggested earlier) to make it consistent
with polyval. I also added a simple test and turned the example from
the docs to a demo.
I'll include this function in the docs eventually, but feel free to do
it (or anyone else).

-- 
RNDr. Jaroslav Hajek
computing expert & GNU Octave developer
Aeronautical Research and Test Institute (VZLU)
Prague, Czech Republic
url: www.highegg.matfyz.cz