I am trying to write a function for P-I curve meansurament of Platt (1980). I used the exemple of nonlinear least squares in R-intro.pdf but I can't finish the analysis. Could you help me? Is there another way to do this analysis? Thanks. I<- c(0,0,100,100,200,200,500,500) P<- c(1.35,-1.41,10.45,9.92,23.99,18.05,9.24,12.31) ps<-23.99 fn<- function (I) (ps*(1 - exp (-I[1]*I/ps))*(exp (-I[2]*I/ps))) plot(I,P) xfit <- seq(0, 500, 100) yfit <- ? Msc. Bruno Pereira Masi Doutorando em Ecologia e Recursos Naturais/UENF CRBio-02 38.047/02 Instrutor Assistente/PDIC # 11014 Instrutor Marine Life/PDIC # 11014 Endereço CV Lattes:lattes.cnpq.br/7389424696175959 Novos endereços, o Yahoo! que você conhece. Crie um email novo com a sua cara @ymail.com ou @rocketmail.com. br.new.mail.yahoo.com/addresses [[alternative HTML version deleted]]