** Non-negative least-squares. **

** X = NNLS(A,b) returns the vector X that solves A*x = b **

** in a least squares sense, subject to x >= 0. **

** **

** **

** A default tolerance of TOL = MAX (SIZE (A)) * NORM (A,1) * EPS **

** is used for deciding when elements of X are less than zero. **

** This can be overridden with X = NNLS(A,b,TOL). **

** **

** **

** [X,W] = NNLS(A,b) also returns dual vector W where **

** w(i) < 0 where x(i) = 0 and w(i) = 0 where x(i) > 0. **

** **

** **

** See also LSCOV , SLASH . **

** **