# generate the random walk
# generate the noise (innovations)
set.seed(6)

# standard normal parameters
mu=0.0
sd=1

#generate n, N(0,1) RVs
n=100
e=rnorm(n=n,mean=mu,sd=sd)

# make plot region 2 x 2
par(mfrow=c(2,2))

# time plot of the innovations
plot(e, type="l")
abline(h=0,col='blue')
plot(e,type='b')
abline(h=0,col='blue')
plot(e,type='o')
abline(h=0,col='blue')

# generate random walk: Y_t = Y_t-1 + e_t
y=cumsum(e)
plot(y,type='o', xlab="Time", ylab="Y_t")
abline(h=0,col='blue')
title("Random Walk")