On Tue, Jun 1, 2010 at 9:59 PM, Shant Ch <sha1...@yahoo.com> wrote: > Hi > > I was trying to have a graph whose axes are X axis: m, Y axis: var[X ((a,b) > in suffix, and (n,d) in the power)]. > > X ((a,b) in suffix, and (n,d) in the power)- X^(n,d) _ (a,b). > > Actually I require many plots involving different values of a,b,n,d, so need > to keep this complicated notation. > The expression() didn't work out for this case. Can anyone help me out. > Thanks, in advance. > Shant > > > > > > > uniroot(function(x) x*(3^x)*log(4)-x*log(4/3)-(3^x)+1, lower = -2, upper = 2, > tol = 0.001 ) > > While using this I am getting the following error. Can anyone please help me > out. > Error in uniroot(function(x) x * (3^x) * log(4) - x * log(4/3) - (3^x) + : > f() values at end points not of opposite sign.
Here is your function: temp.fun <- function(x) { value <- x*(3^x)*log(4)-x*log(4/3)-(3^x)+1 return(value) } look what happens when you do: temp.fun(-2) temp.fun(2) in both cases, it returns a positive value. uniroot() requires "The function values at the endpoints must be of opposite signs (or zero)", hence the error. I believe your function has a lower bound of 0, which is obtained when the input is 0. So one option would be to change your argument to uniroot() so that lower=0. Although the results are not particularly interesting in this case. uniroot(function(x) x*(3^x)*log(4)-x*log(4/3)-(3^x)+1, lower = 0, upper = 2, tol = 0.001 ) HTH, Josh > > Thanks in advance. > > Shant > > > > [[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. > -- Joshua Wiley Senior in Psychology University of California, Riverside http://www.joshuawiley.com/ ______________________________________________ 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.