Hi everyone. I have a non-linear model specified as this (6 variables, a0, S, K, p0, p1, p2):
fit <- nlsLM(formula = dat ~ a0 * exp(-S*(x - 250)) + K + ( C ) ) where C = (p0*exp(-0.5*((x-p1)/p2)^2)) The problem is that I do not know in advance how many component (C) I will have in the model. That means It could be: nlsLM(formula = dat ~ a0 * exp(-S*(x - 250)) + K + ( (p0*exp(-0.5*((x-p1)/p2)^2)) ) ) or nlsLM(formula = dat ~ a0 * exp(-S*(x - 250)) + K + ( (p0*exp(-0.5*((x-p1)/p2)^2)) ) + ( (p0b*exp(-0.5*((x-p1b)/p2b)^2)) )) or nlsLM(formula = dat ~ a0 * exp(-S*(x - 250)) + K + ( (p0*exp(-0.5*((x-p1)/p2)^2)) ) + ( (p0b*exp(-0.5*((x-p1b)/p2b)^2)) + ( (p0c*exp(-0.5*((x-p1c)/p2c)^2)))) So I was wondering if it was possible to dynamically build the formula that I will use in my model? The first part of my model will always be "a0 * exp(-S*(x - 250)) + K", I just want to add a certain number of "components" dynamically. I guess it will be related with "reformulate()" but I can't not find how to make it works. Thank you for your help, Philippe [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.