Initial data commit

Task/Statistics-Normal-distribution/Go/statistics-normal-distribution.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+    "fmt"
+    "math"
+    "math/rand"
+    "strings"
+)
+
+// Box-Muller
+func norm2() (s, c float64) {
+    r := math.Sqrt(-2 * math.Log(rand.Float64()))
+    s, c = math.Sincos(2 * math.Pi * rand.Float64())
+    return s * r, c * r
+}
+
+func main() {
+    const (
+        n     = 10000
+        bins  = 12
+        sig   = 3
+        scale = 100
+    )
+    var sum, sumSq float64
+    h := make([]int, bins)
+    for i, accum := 0, func(v float64) {
+        sum += v
+        sumSq += v * v
+        b := int((v + sig) * bins / sig / 2)
+        if b >= 0 && b < bins {
+            h[b]++
+        }
+    }; i < n/2; i++ {
+        v1, v2 := norm2()
+        accum(v1)
+        accum(v2)
+    }
+    m := sum / n
+    fmt.Println("mean:", m)
+    fmt.Println("stddev:", math.Sqrt(sumSq/float64(n)-m*m))
+    for _, p := range h {
+        fmt.Println(strings.Repeat("*", p/scale))
+    }
+}