To evaluate the efficiency of Levenberg–Marquardt (LM) and Thin-Shell (TS) algorithms with respect to minimum required number of iterations and reached accuracy Matlab functionsfminunc, lsqnonlin, and fminsearch were tested. Based on their performances the function fminunc was chosen as a reference and a means for LM and TS algorithm evaluation. Function fminunc is based on quasi-Newton minimization with numerical gradients [25]. Its description is not the subject of this paperand can be found [26]