add fast pow: O(log n) exponent

numerical/fast_pow.go

@@ -0,0 +1,16 @@
+package numerical
+
+//O(log n) function for pow(x, y)
+func FastPow(n uint, power uint) uint {
+	var res uint = 1
+	for power > 0 {
+
+		if (power & 1) != 0 {
+			res = res * n
+		}
+
+		power = power >> 1
+		n = n * n
+	}
+	return res
+}