From 908b2b3b951409cb5582da8b20dca6aea75d0947 Mon Sep 17 00:00:00 2001
From: Sam Hocevar <sam@hocevar.net>
Date: Tue, 27 Sep 2011 17:09:21 +0000
Subject: [PATCH] real: fix a bug in the real number multiplication when one of
 the arguments is zero.

---
 src/real.cpp | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/real.cpp b/src/real.cpp
index 94c29ed7..19c159c6 100644
--- a/src/real.cpp
+++ b/src/real.cpp
@@ -263,6 +263,13 @@ real real::operator *(real const &x) const
 {
     real ret;
 
+    if (m_signexp << 1 == 0 || x.m_signexp << 1 == 0)
+    {
+        ret = (m_signexp << 1 == 0) ? *this : x;
+        ret.m_signexp ^= x.m_signexp & 0x80000000u;
+        return ret;
+    }
+
     ret.m_signexp = (m_signexp ^ x.m_signexp) & 0x80000000u;
     int e = (m_signexp & 0x7fffffffu) - (1 << 30) + 1
           + (x.m_signexp & 0x7fffffffu) - (1 << 30) + 1;