I have vector X of length N that I want to have a running sum for (called Y). I just need max(Y). I do this with a "for" loop like so: Y <- vector(length=N) Y[1] <- X[1] for (i in 2:N) { Y[i] <- Y[i-1]+X[i] } return(max(Y)) Is there a faster way to do this? Thanks, Sean