y<-rt(100,9)
par(mfrow=c(2,2))
x <- seq(-5,5,0.1)

plot(c(-5,5),c(0,0.45),type="n", bty="l", sub="default", xlab="",ylab="")
lines(x,dt(x,9),lty=2)
rug(y)
lines(density(y,from=-5,to=5,bw="ucv"))

plot(c(-5,5),c(0,0.45),type="n", bty="l", sub="width=0.2", xlab="",ylab="")
lines(x,dt(x,9),lty=2)
rug(y)
lines(density(y,width=0.2, from=-5,to=5))

plot(c(-5,5),c(0,0.45),type="n", bty="l", sub="width=0.5", xlab="",ylab="")
lines(x,dt(x,9),lty=2)
rug(y)
lines(density(y,width=0.5, from=-5,to=5))

plot(c(-5,5),c(0,0.45),type="n", bty="l", sub="width=1.0", xlab="",ylab="")
lines(x,dt(x,9),lty=2)
rug(y)
lines(density(y,width=1.0, from=-5,to=5))