Hello Rick, thanks for your reply, which arrived just as I was leaving for a couple of weeks of travel. I'm back now, and have placed an archive containing the balloon.c source file (it's just one source file, and is a stand-alone program entirely separate from the permutation test plug-in) temporarily at "[
www.mit.edu];. It is of course GPL'ed. The program is self-documenting. To compile it one needs the GNU Scientific Library.
Please let me know when you have it. Many thanks.