x = rnorm(1000,sd=10) 
spectrum(x,method="ar") 
x = rnorm(100000,sd=10)
spectrum(x,method="ar") 
x = rnorm(1000,sd=10) 
mvspec(x) 
y <- ts(x,start=1,frequency=100) ## 1 cycle per 100 observations.
a = stl(y, "periodic") 
plot(a) 
b = a$time.series 
seasonalpart = b[,1] 
trendpart = b[,2] 
residualpart = b[,3] 
plot(1:1000,x,type="l") 
lines(1:1000,trendpart,col="red") 
lines(1:1000,seasonalpart,col="blue") 
spectrum(residualpart,method="ar") 
spectrum(residualpart,log="no",spans=c(3,3)) 
spectrum(seasonalpart,log="no",method="ar")  
frequency(seasonalpart) ## 100