Improve error message to help figure out what is going worng in

http://sparc.koji.fedoraproject.org/koji/getfile?taskID=208037&name=bui
    ld.log

cppad.spec

@@ -16,7 +16,7 @@
 
 Name: cppad
 Version: 20090303.0
-Release: 3%{?dist}
+Release: 4%{?dist}
 Summary: No base package is installed, see %{name}-devel 
 
 Group: Development/Libraries 
@@ -72,6 +72,37 @@ sed -i.stamp test_more/jacobian.cpp \
 sed -i.stamp cppad/local/default.hpp \
 	-e 's/AD<Base>::AD(void) :/& value_(Base(0)), /'
 
+# This patch will no longer be needed once branches/sweep is merged into
+# the CppAD trunk (date is as yet unknown).
+sed -i.stamp cppad/local/fun_construct.hpp \
+	-e '/for(i = 0; i < m; i++)/,$d'
+cat << EOF >> cppad/local/fun_construct.hpp
+# ifndef NDEBUG
+	for(i = 0; i < m; i++) if( taylor_[dep_taddr_[i]] != y[i].value_ )
+	{	using std::endl;
+		std::ostringstream buf;
+		buf << "A dependent variable value is not equal to "
+		    << "its tape evaluation value (perhaps it is nan)" << endl
+		    << "Dependent variable value = " 
+		    <<  y[i].value_ << endl
+		    << "Tape evaluation value    = " 
+		    <<  taylor_[dep_taddr_[i]]  << endl
+		    << "Difference               = " 
+		    <<  y[i].value_ -  taylor_[dep_taddr_[i]]  << endl
+		;
+		CPPAD_ASSERT_KNOWN(
+			0,
+			buf.str().c_str()
+		);
+	}
+# endif
+}
+
+} // END CppAD namespace
+
+# endif
+EOF
+
 # change example/example.cpp to print out machine epsilon 
 cat << EOF > example.sed
 /^int main(void)/N
@@ -130,6 +161,10 @@ rm -rf $RPM_BUILD_ROOT
 
 # ----------------------------------------------------------------------------
 %changelog
+* Sat Jun 20 2009 Brad Bell <bradbell at seanet dot com> 20090303-4
+- Patch cppad/local/fun_construct.hpp to give a more useful error message
+- (so we can figure out why the Fedora 11 build is failing).
+
 * Mon Jun 06 2009 Brad Bell <bradbell at seanet dot com> 20090303-3
 - Patch file test_more/jacobian.cpp (required for versions below 20090606).
 - Patch file cppad/local/default.hpp (required for versions below 20090606).