From 10077c1a0cb72b3342482fa2ac76dbb501ea849c Mon Sep 17 00:00:00 2001
From: John Maddock <john@johnmaddock.co.uk>
Date: Fri, 9 Aug 2013 17:44:48 +0000
Subject: [PATCH] Fix exact sqrt's.

[SVN r85255]
---
 include/boost/multiprecision/detail/default_ops.hpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/boost/multiprecision/detail/default_ops.hpp b/include/boost/multiprecision/detail/default_ops.hpp
index 85c5a021..d47bbf58 100644
--- a/include/boost/multiprecision/detail/default_ops.hpp
+++ b/include/boost/multiprecision/detail/default_ops.hpp
@@ -1149,6 +1149,8 @@ void eval_integer_sqrt(B& s, B& r, const B& x)
    eval_bit_set(t, 2 * g);
    eval_subtract(r, x, t);
    --g;
+   if(eval_get_sign(r) == 0)
+      return;
    int msbr = eval_msb(r);
    do
    {
@@ -1161,6 +1163,8 @@ void eval_integer_sqrt(B& s, B& r, const B& x)
          {
             eval_bit_set(s, g);
             eval_subtract(r, t);
+            if(eval_get_sign(r) == 0)
+               return;
             msbr = eval_msb(r);
          }
       }