program Persamaan Non Linear
root_rf <- function(f, a, b, tol=1e-7, N=100){
iter <- 1
fa <- f(a)
fb <- f(b)
x <- ((fb*a)-(fa*b))/(fb-fa)
fx <- f(x)
while(abs(fx)>tol){
iter <- iter+1
if(iter>N){
warning("iterations maximum exceeded")
break
}
if(fa*fx>0){
a <- x
fa <- fx
} else{
b <- x
fb <- fx
}
x <- (fb*a-fa*b)/(fb-fa)
fx <- f(x)
}
# iterasi nilai x sebagai return value
root <- x
return(list(`function`=f, root=root, iter=iter))
}