"WienerSim" <- function(T=1000, iter=2000,seed = 201705){
set.seed(seed)
x=matrix(rnorm(T*iter),T,iter)
y=apply(x,2,cumsum)
y=y/sqrt(T)
cy=range(y)*1.1
plot(y[,1],xlab='time',ylab='Wiener',type='l',ylim=cy)
for (i in 2:iter){
lines(y[,i],col=i)
}
###end of the program
}