d1 <- rnorm(10000, mean=0, sd=1)
d2 <- rnorm(5000, mean=0, sd=0.5))
d <- c(d1, d2)
png(file="qqp.png", width=600, height=600)
qqnorm(d)
curve(1*x, add=T, col="blue")
dev.off()
png(file="hist.png", width=600, height=600)
hist(d, col="gray50", xlim=c(-4,4) )
dev.off()
