lic: nthrt, n-th root of x

l/lic

@@ -171,6 +171,10 @@ Example:
 (defl factor (n) factors "factorize number" (factor n))
 (defl isprime (n) bool "1 if n is prime, 0 else" (if (prime-number-p n) 1 0))
 
+(defl nthrt (x n) result
+  "take the n-th root of x (n need not be integer)"
+  (expt x (/ 1 n)))
+
 (defl complex (realpart imagpart) complex
   "make a complex number" (complex realpart imagpart))