On 2/24/2019 5:25 AM, malika yassa via R-help wrote:
HELLOplease I want to approximate the solution of the equation f(x)=x*(x-2)+log(x)=0 for that i did this programf <- function(x){x*(x-2)+log(x)} x <- c(1 : 2) f(x) h <- 1e-7 df.dx <- function(x){(f(x + h) - f(x)) / h} df.dx(3/2);df.dx(2) newton <- function(f, tol = 1e-7, x0 = 3/2, N = 100){ h = 1e-7 i = 1; x1 = x0 p = numeric(N) while (i <= N) { df.dx = (f(x + h) - f(x)) / h x1 = (x0 - (f(x0) / df.dx)) p[1] = x1 i = i + 1 if (abs(x1 - x0) < tol) break x0 = x1 } return(p[1 : (i-1)]) } app <- newton(f, x0 = 3/2) but i cann't find this approximation please can you help me? [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
As Bert pointed out there is a no homework policy on this list. But I will point out that when I ran your presented code, I got a lot of warnings. They were not immediately informative (at least to me) because of a subtle programming error in your code. Your main problem (but not your only one) is in the calculation of the derivative of the function inside the while loop. The following line is the problem:
df.dx = (f(x + h) - f(x)) / h I will leave the solution of the problem to you. Dan -- Daniel Nordlund Port Townsend, WA USA ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
