This is the XNU sequence masker written by Jean-Michel Claverie
(jmc@euler.cnrs-mrs.fr) and David States (states@ibc.wustl.edu).

xnu identifies by default short-periodicity repeats within a FASTA-formatted
sequence.  The repeats looked for are ungapped and scored using a PAM120
scoring matrix; hence xnu should only be used to evaluate and mask protein
sequences.  Repeats are chosen for masking by their Karlin-Altschul
expectation.

1) compile with "cc -o xnu xnu.c -lm"
2) test on seq using "xnu seq"; you should get the result stored in seq.xnu
3) xnu.1 is an nroff manual page, viewable as "nroff -man xnu.1 | ul | more"