[task #15803] Match program builds k-d tree and later read from it

[Mohammad Akhlaghi]

Follow-up Comment #9, task #15803 (project gnuastro):

In the process suggested in the previous comment, the coordinates of the two
catalogs will be identical. Although that won't make any difference with
regard to this particular test, a more robust test would be to add noise to
one of the catalogs (or both) before the match. 

Of course, the noise should be much smaller than the matching aperture size so
you can still match (almost) everything.

I had been planning to add this feature (adding noise to table columns) in
Gnuastro for a long time, but the motivation+time+free-mind never converged
together until now! So I am happy to say that it has been implemented in
Commit 5dc054e9d
<https://git.savannah.gnu.org/cgit/gnuastro.git/commit/?id=5dc054e9d>.

So if you install the latest Gnuastro (P.S.), you can run this command on the
'all-sub.fits' table to randomize the positions with a very small scatter of
0.00003 degrees! Feel free to change it as you like ;-)


asttable all-sub.fits \
         -cEDR3Name \
         -c'arith RAJ2000 0.00003 mknoise-sigma' \
         -c'arith DEJ2000 0.00003 mknoise-sigma' \
         -cGmag \
         --colmetadata=ARITH_1,RAJ2000,deg,"Right Ascension" \
         --colmetadata=ARITH_2,DEJ2000,deg,"Declination" \
         --output=all-sub-noised.fits


Of course, Table also has the '--envseed' option to control the random-ness
(and make it reproducible).

P.S. For those that can't build from the Git repository, the latest Gnuastro
tarball and its corresponding PDF manual are available here:
https://akhlaghi.org/gnuastro.pdf
https://akhlaghi.org/gnuastro-latest.tar.lz


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