Hello Patrick, about the next release, a while ago I proposed some code (+tests) to compute the Spearman rank correlation coefficient. I uploaded my code on savannah (http://savannah.gnu.org/bugs/?36199) and it is also available on github (https://github.com/timflutre/spearman). At least one person asked on the mailing list if this coef was implemented (http://savannah.gnu.org/bugs/?37728) so I think it would be useful to add it. I tried to follow the GSL guidelines as close as possible so that it should be possible to integrate the code easily into the next release. I would be glad to help in this matter if necessary.
Best, Tim
