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Re: JPL Planetary Ephemeris DE405

On Thu, 01 Mar 2018 20:36:48 +0100 Ole Streicher wrote:

> Francesco Poli <invernomuto@paranoici.org> writes:
> > I think this is much like digital photographs.
> > A digital photograph represents a scene with objects and/or living
> > beings.
> > But you can modify it to create an image that no longer represents a
> > real scene (think about special effects in movies).
> > See the last FAQ in my above-mentioned essay...
> Citing from there:
> | Depending on which format is extracted from the digital camera and on
> | which form one starts with when making modifications, the source may
> | be in raw format, JPEG, or some other form...
> This would be what I call "raw data", so the original measurements,
> which were used for the several analysis steps that finally lead to the
> ephemeris.
> Some use cases where one would like to change the ephemeris:
>  - I have an improvement in one of the processing steps, and I want to
>    make use of it
>  - I have additional data that I want to merge in an early step of the
>    processing chain
> I can't do this, since I don't have the software available that produced
> the final data (even when the method is described in a paper). And I
> also don't have the raw data available.

If a significant set of possible and reasonable modifications
preferably require these "raw data" and the "processing tools", then...
it really seems that these "raw data" are the source and the
"processing tools" are the build chain.
If one of them (or both) are not available in Debian main (under
DFSG-free terms), then I think the "final data" cannot be in Debian
main, either...

> The idea that one could legally "just change some numbers" is not
> realistic at all: the numbers in the ephemeris data depend on each
> other, and changing them by hand will just make the data
> inconsistent.

In order to enjoy full freedom, you should also have the legal
permission to mess with the data and produce an inconsistent result.
Free software is not (only) about reasonable modifications.
Unreasonable ones should also be allowed.

 There's not a second to spare! To the laboratory!
..................................................... Francesco Poli .
 GnuPG key fpr == CA01 1147 9CD2 EFDF FB82  3925 3E1C 27E1 1F69 BFFE

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