library("forecast")
Loading required package: zoo

Attaching package: 'zoo'
The following objects are masked from 'package:base':

    as.Date, as.Date.numeric
Loading required package: timeDate
Loading required package: methods
This is forecast 7.3 

Google Series (GOOG)

Daily closing price: May 2, 2005 to December 29, 2006.

data <- read.csv("http://ptrckprry.com/course/forecasting/data/google.csv")
GOOG <- data$google
n <- length(GOOG)
time <- 1:n
plot(time, GOOG, type="l", col=2)

Log GOOG

log.GOOG <- log(GOOG)
plot(time, log.GOOG, type="l", col=2)

Acf(log.GOOG)