ut: A              Matrix corresponding to A in the formula above. x              Matrix of solution vectros of the above problem. LS_nnls                   solves multiple nnls problems in parallel. Y              Matrix of inhomogenities, each row represents one nnls                   problm. struct opts opts.display   boolean, if true messages will be printed in console. opts.lambda    lagrangian multiplier for L1 regularization opts.gpu_id    ID of GPU to be used if GPU support is available. opts.use_st