From a843113326ec49f81f6fa7874e21c49a24899ba7 Mon Sep 17 00:00:00 2001
From: Samuel Tardieu <sam@rfc1149.net>
Date: Sun, 28 Dec 2008 11:43:13 +0100
Subject: [PATCH] Optimize erato sieve

We started crossing the numbers at 3*n, while we can start at n^2.
---
 extra/math/primes/erato/erato.factor | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/extra/math/primes/erato/erato.factor b/extra/math/primes/erato/erato.factor
index f4409038bb..effcd7b135 100644
--- a/extra/math/primes/erato/erato.factor
+++ b/extra/math/primes/erato/erato.factor
@@ -8,7 +8,7 @@ IN: math.primes.erato
     2 * 3 + ; inline
 
 : mark-multiples ( i arr -- )
-    [ dup index> [ + ] keep ] dip
+    [ index> [ sq >index ] keep ] dip
     [ length 1 - swap <range> f swap ] keep
     [ set-nth ] curry with each ;