LEVM/LEVMW is an extensive and powerful complex nonlinear least squares program for fitting, simulation, and inversion of frequency and time domain data sets. It has been optimized for analyzing electrochemical, dielectric, or high-resistivity conductive-system data. For users of LEVMW on Vista or Windows 7 a fix to make the HELP file work properly may be downloaded from:http://support.microsoft.com/kb/917607/en-us (Source: http://plato.asu.edu)