Dear all, I want to equalize a symbolic derivative (of a function with two variables) with zero and convert it to a variable, e.g. x. I'm computing the derivative by: (found it in the archive) library(Ryacas) f <- function(x,y) (100-x-y)*x-10*x yacas(f) # register f with yacas Df <- f body(Df) <- yacas(expression(deriv(f(x,y),x)))[[1]] Df R-Output: function (x, y) 100 - x - y - x - 10 Questions : 1. How can I equalize the derivative(140-x-y-x-20) with zero? 2. How can I convert it to x? I want something like: 45-0.5*y=x With only one variable or two non-symbolic variables it's working with uniroot(f, c(-10, 10))$root. Thank you! Immanuel Seeger
[[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.