Hi,
I'm new to R and have a problem with a little test program (see below). Why doesn't <<- in function rk4
The reason is lexical scoping (see FAQ), and I suggest to implement rk4 as function with a return value (see # !!!). BTW there are already a rk4 (and lsoda) functions in the odesolve package.
Thomas P.
Your example formally corrected:
rk4 <- function(x,y,f,h) {
n <- length(y)
hh <- h*0.5
k1 <- f(x,y)
k2 <- f(x,y+k1*hh)
k3 <- f(x,y+k2*hh)
k4 <- f(x,y+k3*h)
y + h/6.0*(k1 + 2.0*k2 + 2.0*k3 + k4) # !!!
}rkf <- function(x,y) {
-y
}rktest <- function(){
y <- 1.0
x <- 0.0
h <- 0.1
for(i in 1:10) {
y <- rk4(x,y,rkf,h) # !!!
print(y)
}
}rktest()
______________________________________________ [EMAIL PROTECTED] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
