try uniroot(), e.g., f <- function (x) x^2 uniroot(function(x, a) f(x) - a, c(0, 10), a = 4)
I hope it helps. Best, Dimitris dennis11 wrote:
Hi, Let's say very simply there is a function: f <- function (x) x^2 which is evaluated with : f(2) Now, I want to do the reverse so I want to now x for f(x) = 4 So, is there a way in R to solve x for some function f(x)=a? I hope I explained it clear. cheers, Dennis
-- Dimitris Rizopoulos Assistant Professor Department of Biostatistics Erasmus Medical Center Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands Tel: +31/(0)10/7043478 Fax: +31/(0)10/7043014 ______________________________________________ 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.
