install.packages("astsa")
library("astsa")
1.
reference: https://bookdown.org/ndphillips/YaRrr/arranging-plots-with-parmfrow-and-layout.html
set.seed(1)
w_t = rnorm(100,0,1)
#w_t2 = filter(w_t, sides=2, filter=rep(1/3, 3))
#figure out what filter function does
par(mfrow=c(1, 2))
ts.plot(w_t, ylab="")
acf(w_t, 20, ylab = 'ACF(w_t)')