src/nnls.f
  From the public domain source code distributed with the book 
  Lawson CL, Hanson RJ (1995). Solving Least Squares
  Problems. Classics in Applied Mathematics. SIAM, Philadelphia, and 
  downloaded from http://www.netlib.org/lawson-hanson/
src/nnnpls.f
  From the public domain source code distributed with the book 
  Lawson CL, Hanson RJ (1995). Solving Least Squares
  Problems. Classics in Applied Mathematics. SIAM, Philadelphia, and 
  downloaded from http://www.netlib.org/lawson-hanson/
  with trivial modifications to allow for non-positive constraints in 
  combination with non-negative constraints. 




