June 2018 Update

Task/Random-numbers/Go/random-numbers.go

@@ -1,17 +1,46 @@
 package main
 
 import (
+    "fmt"
+    "math"
     "math/rand"
+    "strings"
     "time"
 )
 
 const mean = 1.0
 const stdv = .5
+const n = 1000
 
 func main() {
-    var list [1000]float64
+    var list [n]float64
     rand.Seed(time.Now().UnixNano())
     for i := range list {
         list[i] = mean + stdv*rand.NormFloat64()
     }
+    // show computed mean and stdv of list
+    var s, sq float64
+    for _, v := range list {
+        s += v
+    }
+    cm := s / n
+    for _, v := range list {
+        d := v - cm
+        sq += d * d
+    }
+    fmt.Printf("mean %.3f, stdv %.3f\n", cm, math.Sqrt(sq/(n-1)))
+    // show histogram by hdiv divisions per stdv over +/-hrange stdv
+    const hdiv = 3
+    const hrange = 2
+    var h [1 + 2*hrange*hdiv]int
+    for _, v := range list {
+        bin := hrange*hdiv + int(math.Floor((v-mean)/stdv*hdiv+.5))
+        if bin >= 0 && bin < len(h) {
+            h[bin]++
+        }
+    }
+    const hscale = 10
+    for _, c := range h {
+        fmt.Println(strings.Repeat("*", (c+hscale/2)/hscale))
+    }
 }