random.r

par(
  mfrow=c(2,3),
  mar=c(1,1,2,1),
  mgp=c(1, 0.2, 0),
  oma=c(0,0,2,0))

distributeCurve <- function (f, title, samples = 40000, drawSamples = 40) {
  l <- c()
  for (i in 0:samples) {
    r <- f()
    l <- c(l, r)
  }
  s <- c()
  m <- 0
  for (i in 0:drawSamples) {
    l2 <- l[(i/drawSamples) < l]
    l2 <- l2[l2 < ((i+1)/drawSamples)]
    len <- length(l2)
    s <- c(s, len)
    m <- max(m, len)
  }
  random <- function (x) {
    return (s[ceiling(x * drawSamples)])
  }
  curve(random, 0.01, 0.99, 50,
    main=title,
    ylim=c(0, 1.2 * m),
    yaxt="n",
    ylab="")
}

r <- function () {
  return (runif(1))
}
distributeCurve(function () {
  return (r());
}, "r()")

distributeCurve(function () {
  return (r() * r())
}, "r() * r()")

distributeCurve(function () {
  return (r() ^ 2)
}, "Math.pow(r(), 2)")

distributeCurve(function () {
  return (r() + r())/2
}, "(r() + r())/2")

distributeCurve(function () {
  return (0.3*r() + 0.7*r())
}, "0.3*r() + 0.7*r()")

distributeCurve(function () {
  return (r() + r() + r())/3
}, "(r() + r() + r())/3")

title(
  "different distribution of Math.random()",
  outer=T)