Jake Vanderplas, writing on AstroBetter, discusses the licensing of scientific code, providing the following suggestions:

  1. Always license your code. Unlicensed code is closed code, so any open license is better than none (but see #2).
  2. Always use a GPL-compatible license. GPL-compatible licenses ensure broad compatibility for your code, and include GPL, new BSD, MIT, and others (but see #3).
  3. Always use a permissive, BSD-style license. A permissive license such as new BSD or MIT is preferable to a copyleft license such as GPL or LGPL.

I agree. IDLdoc, mgunit, rIDL, my library, and all the other open source code I have on GitHub uses a BSD-style license.