Hi all, I am coding for finding the root of f(x)= phi(x) -alpha where phi(x) is the cumulative density function and alpha is constant . The problem right now is I can't get the "initialX" representing the root out of the while loop when ending , it seems to me it disappear when the loop ends accroding to the error message. I need help . Please suggest the cause or solution to this problem. Thanks.
# code #generate target function (phi(x)-alpha) (allow input x and alpha) target<-function(x,alpha){ pnorm(x)-alpha } #generate the first derivative of the of the target function firstDerivative<-function(x){ exp(-(x^2)/2)/sqrt(2*pi) } # Finding the root by Newton method rootFinding<-function(initialX,setAlpha){ while(target(initialX,setAlpha)!=0){ initialX<-initialX-(target(initialX,setAlpha)/firstfirstDerivative(initialX) } initialX } -- View this message in context: http://www.nabble.com/Newton-method-iteration-problem-tf4701085.html#a13439031 Sent from the R help mailing list archive at Nabble.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.