update the optimize interface

gtsam/linear/IterativeSolver.h

@@ -68,6 +68,10 @@ namespace gtsam {
 
     /* interface to the nonlinear optimizer  */
     virtual VectorValues optimize () = 0;
+
+    /* interface to the nonlinear optimizer  */
+    virtual VectorValues optimize (const VectorValues &initial) = 0;
+
     /* update interface to the nonlinear optimizer  */
     virtual void replaceFactors(const GaussianFactorGraph::shared_ptr &factorGraph, const double lambda) {}
   };

gtsam/linear/SubgraphSolver.cpp

@@ -78,6 +78,11 @@ VectorValues SubgraphSolver::optimize() {
   return pc_->x(ybar);
 }
 
+VectorValues SubgraphSolver::optimize(const VectorValues &initial) {
+  // the initial is ignored in this case ...
+  return optimize();
+}
+
 void SubgraphSolver::initialize(const GaussianFactorGraph &jfg)
 {
   GaussianFactorGraph::shared_ptr Ab1 = boost::make_shared<GaussianFactorGraph>(),

gtsam/linear/SubgraphSolver.h

@@ -72,6 +72,7 @@ public:
 
   virtual ~SubgraphSolver() {}
   virtual VectorValues optimize () ;
+  virtual VectorValues optimize (const VectorValues &initial) ;
 
 protected: