approx function to do linear
extrapolation.
approx in R does not support extrapolation at
all, and it is buggy in S-Plus 6.
approxExtrap(x, y, xout, method = "linear", n = 50, rule = 2, f = 0, ties = "ordered", na.rm = FALSE)
TRUE to remove
NAs in
x and
y before proceeding
Duplicates in
x (and corresponding
y elements) are removed
before using
approx.
xout
Frank Harrell
approxExtrap(1:3,1:3,xout=c(0,4))