fix comments

gtsam_unstable/linear/LinearCost.h

@@ -25,8 +25,8 @@ namespace gtsam {
 typedef Eigen::RowVectorXd RowVector;
 
 /**
- * This class defines a linear inequality constraint g(x)<=0,
- * inheriting JacobianFactor with the special Constrained noise model
+ * This class defines a linear cost function c'x
+ * which is a JacobianFactor with only one row
  */
 class LinearCost: public JacobianFactor {
 public:

gtsam_unstable/linear/LinearInequality.h

@@ -83,7 +83,8 @@ public:
 
   /** Construct an n-ary factor
    * @tparam TERMS A container whose value type is std::pair<Key, Matrix>, specifying the
-   *         collection of keys and matrices making up the factor. */
+   *         collection of keys and matrices making up the factor.
+   *         In this inequality factor, each matrix must have only one row!! */
   template<typename TERMS>
   LinearInequality(const TERMS& terms, double b, Key dualKey) :
       Base(terms, (Vector(1) << b).finished(), noiseModel::Constrained::All(1)), dualKey_(