ce curve from the difference between two consecutive iterative solutions (Consec_error). It performs a linear fit of the log of Consec_error for opts.sample previous iterates and if the error between the linear fit and the log of the consecutive error is smaller than opts.tol_ the algorithm can use this information to accurately estimate the true error. If the true error is below opts.tol the algorithm stops for the nnls-sub-problem in question and puts the current solution into the output array.</p><h2 id=