moved [symbol] function to LinearFactor

cpp/LinearFactor.cpp

@@ -237,7 +237,7 @@ LinearFactor::eliminate(const string& key)
   FOREACH_PAIR(j,A,As) {
     if (j != key) {
       const size_t nj = A.size2();   // get dimension of variable
-      cg->add(j, sub(A,0,n,0,nj));   // add a parent to conditional gaussian
+      cg->add(j, sub(A,0,n,0,nj));   // add a parent to conditional Gaussian
       lf->insert(j,sub(A,n,m,0,nj)); // insert into linear factor
     }
   }
@@ -245,3 +245,13 @@ LinearFactor::eliminate(const string& key)
 }
 
 /* ************************************************************************* */
+namespace gtsam {
+
+	string symbol(char c, int index) {
+		stringstream ss;
+		ss << c << index;
+		return ss.str();
+	}
+
+}
+/* ************************************************************************* */

cpp/LinearFactor.h

@@ -228,4 +228,12 @@ public:
 
 /* ************************************************************************* */
 
+/**
+ * creates a C++ string a la "x3", "m768"
+ * @param c the base character
+ * @param index the integer to be added
+ * @return a C++ string
+ */
+std::string symbol(char c, int index);
+
 } // namespace gtsam