Hi R-help; In using nlme, I often encounter the following error message: Error in nlme.formula(model = response ~ ......, data = ... : Step halving factor reduced below minimum in PNLS step Resetting the pnlsTol default value does not solve the problem. Any suggestions or workarouds for solving the problem? TIA, Richard -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._