d   calculate least standard deviation instead of L2-norm opts.sample    Read about convergence check below! opts.tol       - opts.tol_      -</p><p>Output X              Matrix of approximations of the solutions to the                   nnls problems. Each row is one solution. G              Gramian matrix.</p><p>Convergence check: LS_nnls checks for each of the nnls subproblem if a certain accuracy is reached. It does that no like usually by checking the norm of the gradient, but by guessing the convergen