R help - Aug 2008 - Trying to run simple survival program in R

> Hey,
>
> I am just starting to learn R now and I typed in this simple survival
> program:
>   
>    library(survival)
>    t <- c(10,13,18,19,23,30,36,38,54,56,59,75,93,97,104,107,107,107)
>    c <- c(1,0,0,1,0,1,1,0,0,0,1,1,1,1,0,1,0,0)
>    data <- Surv(t,c)
>    km <- survfit(data)       
>    summary(km)
>    Call: survfit(formula = data)
 It is best to use a formula with the survfit program; the preferred way to call
it would be
 
 > km <- survfit(Surv(t, c) ~1)
 > print(km)
 > plot(km)
 
 etc.
 
    Terry Therneau