> Is this code snippet in lcp.cpp correct (specifically, line 1316)? > 1316 x[i] += s * dirf; why do you think it's wrong? if you think that dirf should be replaced by delta_x[i], then i don't think so, see line 1229: // note that delta_x[i] = dirf, but we wont bother to set it what are the causes/effects of your problem? russ. -- Russell Smith http://www.q12.org