Data commit

Task/Average-loop-length/Go/average-loop-length.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+    "fmt"
+    "math"
+    "math/rand"
+)
+
+const nmax = 20
+
+func main() {
+    fmt.Println(" N    average    analytical    (error)")
+    fmt.Println("===  =========  ============  =========")
+    for n := 1; n <= nmax; n++ {
+        a := avg(n)
+        b := ana(n)
+        fmt.Printf("%3d  %9.4f  %12.4f  (%6.2f%%)\n",
+            n, a, b, math.Abs(a-b)/b*100)
+    }
+}
+
+func avg(n int) float64 {
+    const tests = 1e4
+    sum := 0
+    for t := 0; t < tests; t++ {
+        var v [nmax]bool
+        for x := 0; !v[x]; x = rand.Intn(n) {
+            v[x] = true
+            sum++
+        }
+    }
+    return float64(sum) / tests
+}
+
+func ana(n int) float64 {
+    nn := float64(n)
+    term := 1.
+    sum := 1.
+    for i := nn - 1; i >= 1; i-- {
+        term *= i / nn
+        sum += term
+    }
+    return sum
+}