Go example added to kitchen sink demo

demo/kitchen-sink/docs/golang.go

@@ -0,0 +1,34 @@
+// Concurrent computation of pi.
+// See http://goo.gl/ZuTZM.
+//
+// This demonstrates Go's ability to handle
+// large numbers of concurrent processes.
+// It is an unreasonable way to calculate pi.
+package main
+
+import (
+    "fmt"
+    "math"
+)
+
+func main() {
+    fmt.Println(pi(5000))
+}
+
+// pi launches n goroutines to compute an
+// approximation of pi.
+func pi(n int) float64 {
+    ch := make(chan float64)
+    for k := 0; k <= n; k++ {
+        go term(ch, float64(k))
+    }
+    f := 0.0
+    for k := 0; k <= n; k++ {
+        f += <-ch
+    }
+    return f
+}
+
+func term(ch chan float64, k float64) {
+    ch <- 4 * math.Pow(-1, k) / (2*k + 1)
+}