### Simulate the three models in Problem 2.6 and save them.

# a.


# Simulated in ASTSA.  Splus will not simulate non-stationary time series.

par(mfrow=c(2,3))

x <- scan("E:\\Stat207\\Homework\\Ch2\\Problem2.6\\data1.dat")
tsplot(x,main="AR(2), ar = c(-1.6,-.64)")
acf(x, 20)
acf(x, 20, "partial")


# b.

x <- arima.sim(400,model=list(ar=c(.4,.45)))
write(x, file="E:\\Stat207\\Homework\\Ch2\\Problem2.6\\data2.dat", ncolumns=1, append=F)
tsplot(x,main="AR(2), ar = c(.4,.45)")
acf(x, 20)
acf(x, 20, "partial")


# c.

par(mfrow=c(2,3))

x <- arima.sim(400,model=list(ar=c(1.2,-.85)))
write(x, file="E:\\Stat207\\Homework\\Ch2\\Problem2.6\\data3.dat", ncolumns=1, append=F)
tsplot(x,main="AR(2), ar = c(1.2,-.85)")
acf(x, 20)
acf(x, 20, "partial")