healpix (finally) becomes free software :))))))))

Use of Healpix, camb, CLASS, cosmomc, compilers, etc.
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Boud Roukema
Posts: 86
Joined: February 24 2005
Affiliation: Torun Centre for Astronomy, University of Nicolaus Copernicus
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healpix (finally) becomes free software :))))))))

Post by Boud Roukema » September 05 2005

After suggestions from the Toruń cosmology group 18 months ago:

http://cosmo.torun.pl/pipermail/cosmo-torun/

that the WMAP data should be readable using free software (free as in speech - http://www.gnu.org) and hence that having a non-free licence for the official healpix software package was not very constructive, it seems that the official group have finally accepted peer pressure and released their package under the GPL:

http://sourceforge.net/projects/healpix/ (version 2.00)
# License: GNU General Public License (GPL)
- click on download to download the package

For anyone interested in what the healpix projection/pixelisation is all about, you can read the following three articles, chronologically:
(For the curious: the chronology of 0409533 and 0409513 is correct: 0409533 was written first, sent to the other group of authors with a proposal for coauthorship, who responded by publishing 0409513 independently without any warning - anyway, the important thing is that the algorithm is clearly documented and public.)

More importantly, in astro-ph/0412607 we point out that the healpix projection/pixelisation is a combined cylindrical equal-area projection + a Collignon (1865) projection, followed by the hierarchical pixelisation of 12 squares. (There's also a generalisation of this class of projections in the paper.)

And there are at least three independent GPL software packages: So the projection is now well understood and there are several GPL versions of the software. :)))

All's well that ends well.

David Larson
Posts: 11
Joined: September 25 2004
Affiliation: Johns Hopkins University

healpix (finally) becomes free software :))))))))

Post by David Larson » September 09 2005

Does anyone know if there's a forum for discussing improvements or additions to Healpix?

Hans Kristian Eriksen
Posts: 59
Joined: September 25 2004
Affiliation: ITA, University of Oslo
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Re: healpix (finally) becomes free software :))))))))

Post by Hans Kristian Eriksen » September 09 2005

David Larson wrote:Does anyone know if there's a forum for discussing improvements or additions to Healpix?
There isn't any official forum, if that's what you are asking for. But if you have any specific suggestions in mind, I would think sending an email to Eric Hivon and/or Kris Gorski would be a natural approach. Or you could of course always post it in this forum -- somebody is sure to pick it up here.

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