fix(?) a bug in factor_lehman

SPancratz · Jun 29, 2012 · c76b9a2 · c76b9a2
1 parent e520083
commit c76b9a2
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Showing 2 changed files with 10 additions and 1 deletion.
diff --git a/ulong_extras/factor_lehman.c b/ulong_extras/factor_lehman.c
@@ -58,7 +58,7 @@ mp_limb_t n_factor_lehman(mp_limb_t n)
     for (k = 1; k <= cuberoot + 1; k++)
     {
         mp_limb_t x = (mp_limb_t) ceil(2.0*sqrt((double) k)*sqrt((double) n));
-        mp_limb_t end = x + (mp_limb_t) floor(1.0 + pow(n, 1.0/6.0)/((double) 4.0*sqrt((double) k)));
+        mp_limb_t end = x + (mp_limb_t) floor(1.0 + pow(n, 1.0/6.0)/((double) 4.0*sqrt((double) k))) + 1;
         mp_limb_t sub = k*n*4;
 
         for ( ; x <= end; x++)

diff --git a/ulong_extras/test/t-factor_lehman.c b/ulong_extras/test/t-factor_lehman.c
@@ -78,6 +78,15 @@ int main(void)
       n1 = n_nextprime(n1, 1);
       n2 = n_nextprime(n2, 1);
 
+      /* test a specific bug */
+#if FLINT64
+      if (i == 0)
+      {
+           n1 = 72528697;
+           n2 = 73339073;
+      }
+#endif
+
       n = n1*n2;
 
       n3 = n_factor_lehman(n);