--- p_square_cumulative_distribution.cpp	2008-11-11 18:06:12.000000000 +0100
+++ p_square_cumulative_distribution.cpp.fixed	2008-11-13 16:37:03.000000000 +0100
@@ -63,7 +63,7 @@
     {
         // problem with small results: epsilon is relative (in percent), not absolute!
         if ( histogram[i].second > 0.001 )
-            BOOST_CHECK_CLOSE( 0.5 * (1.0 + my_erf( histogram[i].first / sqrt(2.0) )), histogram[i].second, epsilon );
+            BOOST_CHECK_CLOSE( 0.5 * (1.0 + my_erf( histogram[i].first / std::sqrt(2.0) )), histogram[i].second, epsilon );
     }
 }