From 4ac720f00db3fae138ba8fe0af3cc3d0524b71c2 Mon Sep 17 00:00:00 2001
From: Gerald Teschl <gerald.teschl@univie.ac.at>
Date: Mon, 21 Oct 2024 13:01:36 +0200
Subject: [PATCH] Update primes.py

---
 kryptools/primes.py | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/kryptools/primes.py b/kryptools/primes.py
index 6880e9f..4beb38c 100644
--- a/kryptools/primes.py
+++ b/kryptools/primes.py
@@ -125,12 +125,15 @@ def iroot(k: int, n: int) -> int:
         return n
     if k == 2:
         return isqrt(n)
-    rr = isqrt(n)
+    r = isqrt(n)
+    while r**k >= n:
+        rr = r
+        r = isqrt(r)
     r =rr + 1
     k1 = k-1
     while rr < r:
         r = rr
-        rr = (k1 * r + n // r ** k1) // k # Newton iteration
+        rr = (k1 * rr + n // rr ** k1) // k # Newton iteration
     return r
 
 def perfect_power(n: int) -> tuple|None: