newton<-function(x0, eps) {
    repeat {
	x1<-x0 - fun(x0)/derf(x0)
	if(abs(x0 - x1) < eps)
	    break
	x0<-x1
    }
    x1
}
fun<-function(x){
    x * exp(-x) - 0.2
}

derf=function(x) {
    (1-x)*exp(-x)
}


x<-seq(-2, 2, , 20)
fun(x)
x<-seq(-1, 4, , 20)
plot(x, fun(x))
abline(h=0, col=2)
newton(0.0, .000001)
newton(2.0, .000001)

 newton<-function(x0, eps) {
     k<-0
     repeat {
	 k<-k + 1
	 x1<-x0 - fun(x0)/derf(x0)
	 if(abs(x0 - x1)< eps)
	     break
	 x0<-x1
	 cat("Iteration No: ", k, "Current iterate = ",x1 , fill=T)
	 }
	 x1
     }
     
#> source("newton.s")
# newton(0.0, .000001)



newton2<- function(fun, derf, x0, eps){
    k<- 0
    repeat {
	k<- k + 1
	x1<- x0 - fun(x0)/derf(x0)
	if(abs(x0 - x1)< eps)
	    break
	x0<- x1
	cat("Iteration No: ", k, "Current iterate = ",x1 , fill=T)
    }
    x1
}

myfun<- function(x){
x * exp(- x) - 0.2
}

deriv<- function(x){
(1 - x) * exp(- x)
}