Solve argmin_x || Ax - b ||_2 for x>=0. This is a wrapper for a FORTAN non-negative least squares solver.
A : ndarray
b : ndarray
x : ndarray
rnorm : float
The FORTRAN code was published in the book below. The algorithm is an active set method. It solves the KKT (Karush-Kuhn-Tucker) conditions for the non-negative least squares problem.
Lawson C., Hanson R.J., (1987) Solving Least Squares Problems, SIAM