path<-"http://datayyy.com/data_R/"
infile<-paste0(path,"nStockVSportfolioRisk.RData")
a<-load(url(infile))
x<-.x$nStocks
y<-.x$sigma
title<-"The number of stock vs. the portfolio risk"
yLabel<-"Portfolio risk (sigma)"
plot(log(n),y,xaxt="n",xlab="n",ylab=yLabel,type="b",lwd=4,main=title)
axis(1, at = log(n), labels = n)