June 2018 Update

Task/Random-numbers/Scala/random-numbers-2.scala

@@ -0,0 +1,25 @@
+val distrubution = {
+  def randomNormal = 1.0 + 0.5 * scala.util.Random.nextGaussian
+
+  def normalDistribution(a: Double): Stream[Double] = a #:: normalDistribution(randomNormal)
+
+  normalDistribution(randomNormal)
+}
+
+/*
+ * Let's test it
+ */
+  def calcAvgAndStddev[T](ts: Iterable[T])(implicit num: Fractional[T]): (T, Double) = {
+    val mean: T =
+      num.div(ts.sum, num.fromInt(ts.size)) // Leaving with type of function T
+
+    // Root of mean diffs
+    val stdDev = sqrt(ts.map { x =>
+      val diff = num.toDouble(num.minus(x, mean))
+      diff * diff
+    }.sum / ts.size)
+
+    (mean, stdDev)
+  }
+
+println(calcAvgAndStddev(distrubution.take(1000))) // e.g. (1.0061433267806525,0.5291834867560893)