diff --git a/.cproject b/.cproject
index 798e3502d..063d544b5 100644
--- a/.cproject
+++ b/.cproject
@@ -335,6 +335,14 @@
 <useDefaultCommand>true</useDefaultCommand>
 <runAllBuilders>true</runAllBuilders>
 </target>
+<target name="testConditionalGaussian.run" path="cpp" targetID="org.eclipse.cdt.build.MakeTargetBuilder">
+<buildCommand>make</buildCommand>
+<buildArguments></buildArguments>
+<buildTarget>testConditionalGaussian.run</buildTarget>
+<stopOnError>true</stopOnError>
+<useDefaultCommand>true</useDefaultCommand>
+<runAllBuilders>true</runAllBuilders>
+</target>
 <target name="install" path="" targetID="org.eclipse.cdt.build.MakeTargetBuilder">
 <buildCommand>make</buildCommand>
 <buildArguments></buildArguments>
diff --git a/cpp/ConditionalGaussian.cpp b/cpp/ConditionalGaussian.cpp
index fa7dc0b46..e681ba500 100644
--- a/cpp/ConditionalGaussian.cpp
+++ b/cpp/ConditionalGaussian.cpp
@@ -54,18 +54,16 @@ void ConditionalGaussian::print(const string &s) const
 }    
 
 /* ************************************************************************* */
-Vector ConditionalGaussian::solve(const FGConfig& x)
-{
-  Vector rhs = d_;
-  for(map<string, Matrix>::const_iterator it = parents_.begin() ; it != parents_.end() ; it++ ) {
-    const string&   j = it->first;
-    const Matrix& Aj = it->second;
-    rhs -= Aj*x[j];
-    
-  }
-  Vector result = backsubstitution(R_, rhs);
-  return result;
-  
+Vector ConditionalGaussian::solve(const FGConfig& x) const {
+	Vector rhs = d_;
+	for (map<string, Matrix>::const_iterator it = parents_.begin(); it
+			!= parents_.end(); it++) {
+		const string& j = it->first;
+		const Matrix& Aj = it->second;
+		rhs -= Aj * x[j];
+	}
+	Vector result = backsubstitution(R_, rhs);
+	return result;
 }    
 
 /* ************************************************************************* */
diff --git a/cpp/ConditionalGaussian.h b/cpp/ConditionalGaussian.h
index 1fca89b5f..84d5e5560 100644
--- a/cpp/ConditionalGaussian.h
+++ b/cpp/ConditionalGaussian.h
@@ -107,7 +107,7 @@ namespace gtsam {
      * @param x configuration in which the parents values (y,z,...) are known
      * @return solution x = R \ (d - Sy - Tz - ...)
      */
-    Vector solve(const FGConfig& x);
+    Vector solve(const FGConfig& x) const;
 
     /**
      * adds a parent