Also noted for the future:
http://www.nr.com/public-domain.html
Public Domain Software
In general, the Numerical Recipes routines are NOT in the public domain, and are NOT available for use without a valid license. However, a few small parts of Numerical Recipes have been put into the public domain. These can be freely copied and redistributed:
Utility files for C:
* nrutil.c
* nrutil.h
* complex.c
* complex.h
Wavelet routines in C:
* wt1.c
* daub4.c
* pwt.c
* pwtset.c
* wtn.c