Added NthRoot{,64} methods.

ints/math.go

@@ -72,6 +72,16 @@ func Norm64(i int64) int64 {
 	return 0
 }
 
+// NthRoot returns the nth root of i.
+func NthRoot(i, n int) int {
+	return int(math.Pow(float64(i), 1/float64(n)))
+}
+
+// NthRoot64 returns the nth root of i.
+func NthRoot64(i, n int64) int64 {
+	return int64(math.Pow(float64(i), 1/float64(n)))
+}
+
 // SubAbs subtracts a from b and returns the absolute value of the result.
 func SubAbs(a, b int) int {
 	if a > b {