diff --git a/include/core/problem/problem.h b/include/core/problem/problem.h
index b9befc35a036142b87eb48ccdf9973fc16d818b9..d7133cddc09f99aad05d0ada7c35ffbe88513c25 100644
--- a/include/core/problem/problem.h
+++ b/include/core/problem/problem.h
@@ -325,6 +325,11 @@ class Problem : public std::enable_shared_from_this<Problem>
 
     public:
         // Print and check ---------------------------------------
+        void print(int depth, //
+                   std::ostream& stream ,
+                   bool constr_by, //
+                   bool metric, //
+                   bool state_blocks) const;
         /**
          * \brief print wolf tree
          * \param depth :        levels to show ( 0: H, T, M : 1: H:S:p, T:F, M:L ; 2: T:F:C ; 3: T:F:C:f ; 4: T:F:C:f:c )
@@ -340,11 +345,8 @@ class Problem : public std::enable_shared_from_this<Problem>
                    bool constr_by = false, //
                    bool metric = true, //
                    bool state_blocks = false) const;
-        std::string printToString(int depth = 4, //
-                          bool constr_by = false,   //
-                          bool metric = true,       //
-                          bool state_blocks = false) const;
-        bool check(int verbose_level = 0) const;
+        bool check(int verbose_level) const;
+        bool check(bool verbose, std::ostream& stream) const;
 
 };
 
diff --git a/src/problem/problem.cpp b/src/problem/problem.cpp
index 8ba9bd9acab0ef571d8859b361b369428ddeba4f..8a694beb4c8145d5d7253f0c8687ce5f6e45d82c 100644
--- a/src/problem/problem.cpp
+++ b/src/problem/problem.cpp
@@ -872,55 +872,53 @@ void Problem::saveMap(const std::string& _filename_dot_yaml, const std::string&
     getMap()->save(_filename_dot_yaml, _map_name);
 }
 
-void Problem::print(int depth, bool constr_by, bool metric, bool state_blocks) const
+void Problem::print(int depth, std::ostream& stream, bool constr_by, bool metric, bool state_blocks) const
 {
-    using std::cout;
-    using std::endl;
 
-    cout << endl;
-    cout << "P: wolf tree status ---------------------" << endl;
-    cout << "Hardware" << ((depth < 1) ? ("   -- " + std::to_string(getHardware()->getSensorList().size()) + "S") : "")  << endl;
+    stream << std::endl;
+    stream << "P: wolf tree status ---------------------" << std::endl;
+    stream << "Hardware" << ((depth < 1) ? ("   -- " + std::to_string(getHardware()->getSensorList().size()) + "S") : "")  << std::endl;
     if (depth >= 1)
     {
         // Sensors =======================================================================================
         for (auto S : getHardware()->getSensorList())
         {
-            cout << "  Sen" << S->id() << " " << S->getType() << " \"" << S->getName() << "\"";
+            stream << "  Sen" << S->id() << " " << S->getType() << " \"" << S->getName() << "\"";
             if (depth < 2)
-                cout << " -- " << S->getProcessorList().size() << "p";
-            cout << endl;
+                stream << " -- " << S->getProcessorList().size() << "p";
+            stream << std::endl;
             if (metric && state_blocks)
             {
-                cout << "    sb: ";
+                stream << "    sb: ";
                 for (auto& _key : S->getStructure())
                 {
                     auto key = std::string(1,_key);
                     auto sb = S->getStateBlock(key);
-                    cout << key << "[" << (S->isStateBlockDynamic(key) ? "Dyn" : "Sta") << "," << (sb->isFixed() ? "Fix" : "Est") << "] = ( " << sb->getState().transpose() << " ); ";
+                    stream << key << "[" << (S->isStateBlockDynamic(key) ? "Dyn" : "Sta") << "," << (sb->isFixed() ? "Fix" : "Est") << "] = ( " << sb->getState().transpose() << " ); ";
                 }
-                cout << endl;
+                stream << std::endl;
             }
             else if (metric)
             {
-                cout << "    ( ";
+                stream << "    ( ";
                 for (auto& _key : S->getStructure())
                 {
                     auto key = std::string(1,_key);
                     auto sb = S->getStateBlock(key);
-                    cout << sb->getState().transpose() << " ";
+                    stream << sb->getState().transpose() << " ";
                 }
-                cout << ")" << endl;
+                stream << ")" << std::endl;
             }
             else if (state_blocks)
             {
-                cout << "    sb: ";
+                stream << "    sb: ";
                 for (auto& _key : S->getStructure())
                 {
                     auto key = std::string(1,_key);
                     auto sb = S->getStateBlock(key);
-                    cout << key << "[" << (S->isStateBlockDynamic(key) ? "Dyn" : "Sta") << "," << (sb->isFixed() ? "Fix" : "Est") << "]; ";
+                    stream << key << "[" << (S->isStateBlockDynamic(key) ? "Dyn" : "Sta") << "," << (sb->isFixed() ? "Fix" : "Est") << "]; ";
                 }
-                cout << endl;
+                stream << std::endl;
             }
             if (depth >= 2)
             {
@@ -929,126 +927,126 @@ void Problem::print(int depth, bool constr_by, bool metric, bool state_blocks) c
                 {
                     if (p->isMotion())
                     {
-                        std::cout << "    PrcM" << p->id() << " " << p->getType() << " \"" << p->getName() << "\"" << endl;
+                        stream << "    PrcM" << p->id() << " " << p->getType() << " \"" << p->getName() << "\"" << std::endl;
                         ProcessorMotionPtr pm = std::static_pointer_cast<ProcessorMotion>(p);
                         if (pm->getOrigin())
-                            cout << "      o: C" << pm->getOrigin()->id() << " - " << (pm->getOrigin()->getFrame()->isKeyOrAux() ? (pm->getOrigin()->getFrame()->isKey() ? "  KFrm" : "  AFrm" ) : "  Frm")
-                            << pm->getOrigin()->getFrame()->id() << endl;
+                            stream << "      o: C" << pm->getOrigin()->id() << " - " << (pm->getOrigin()->getFrame()->isKeyOrAux() ? (pm->getOrigin()->getFrame()->isKey() ? "  KFrm" : "  AFrm" ) : "  Frm")
+                            << pm->getOrigin()->getFrame()->id() << std::endl;
                         if (pm->getLast())
-                            cout << "      l: C" << pm->getLast()->id() << " - " << (pm->getLast()->getFrame()->isKeyOrAux() ? (pm->getLast()->getFrame()->isKey() ? "  KFrm" : " AFrm") : "  Frm")
-                            << pm->getLast()->getFrame()->id() << endl;
+                            stream << "      l: C" << pm->getLast()->id() << " - " << (pm->getLast()->getFrame()->isKeyOrAux() ? (pm->getLast()->getFrame()->isKey() ? "  KFrm" : " AFrm") : "  Frm")
+                            << pm->getLast()->getFrame()->id() << std::endl;
                         if (pm->getIncoming())
-                            cout << "      i: C" << pm->getIncoming()->id() << endl;
+                            stream << "      i: C" << pm->getIncoming()->id() << std::endl;
                     }
                     else
                     {
-                        cout << "    PrcT" << p->id() << " " << p->getType() << " \"" << p->getName() << "\"" << endl;
+                        stream << "    PrcT" << p->id() << " " << p->getType() << " \"" << p->getName() << "\"" << std::endl;
                         ProcessorTrackerPtr pt = std::dynamic_pointer_cast<ProcessorTracker>(p);
                         if (pt)
                         {
                             if (pt->getOrigin())
-                                cout << "      o: C" << pt->getOrigin()->id() << " - " << (pt->getOrigin()->getFrame()->isKeyOrAux() ? (pt->getOrigin()->getFrame()->isKey() ? "  KFrm" : " AFrm") : "  Frm")
-                                << pt->getOrigin()->getFrame()->id() << endl;
+                                stream << "      o: C" << pt->getOrigin()->id() << " - " << (pt->getOrigin()->getFrame()->isKeyOrAux() ? (pt->getOrigin()->getFrame()->isKey() ? "  KFrm" : " AFrm") : "  Frm")
+                                << pt->getOrigin()->getFrame()->id() << std::endl;
                             if (pt->getLast())
-                                cout << "      l: C" << pt->getLast()->id() << " - " << (pt->getLast()->getFrame()->isKeyOrAux() ? (pt->getLast()->getFrame()->isKey() ? "  KFrm" : " AFrm") : "  Frm")
-                                << pt->getLast()->getFrame()->id() << endl;
+                                stream << "      l: C" << pt->getLast()->id() << " - " << (pt->getLast()->getFrame()->isKeyOrAux() ? (pt->getLast()->getFrame()->isKey() ? "  KFrm" : " AFrm") : "  Frm")
+                                << pt->getLast()->getFrame()->id() << std::endl;
                             if (pt->getIncoming())
-                                cout << "      i: C" << pt->getIncoming()->id() << endl;
+                                stream << "      i: C" << pt->getIncoming()->id() << std::endl;
                         }
                     }
                 } // for p
             }
         } // for S
     }
-    cout << "Trajectory" << ((depth < 1) ? (" -- " + std::to_string(getTrajectory()->getFrameList().size()) + "F") : "")  << endl;
+    stream << "Trajectory" << ((depth < 1) ? (" -- " + std::to_string(getTrajectory()->getFrameList().size()) + "F") : "")  << std::endl;
     if (depth >= 1)
     {
         // Frames =======================================================================================
         for (auto F : getTrajectory()->getFrameList())
         {
-            cout << (F->isKeyOrAux() ? (F->isKey() ? "  KFrm" : " AFrm") : "  Frm") << F->id() << ((depth < 2) ? " -- " + std::to_string(F->getCaptureList().size()) + "C  " : "");
+            stream << (F->isKeyOrAux() ? (F->isKey() ? "  KFrm" : " AFrm") : "  Frm") << F->id() << ((depth < 2) ? " -- " + std::to_string(F->getCaptureList().size()) + "C  " : "");
             if (constr_by)
             {
-                cout << "  <-- ";
+                stream << "  <-- ";
                 for (auto cby : F->getConstrainedByList())
-                    cout << "Fac" << cby->id() << " \t";
+                    stream << "Fac" << cby->id() << " \t";
             }
-            cout << endl;
+            stream << std::endl;
             if (metric)
             {
-                cout << (F->isFixed() ? "    Fix" : "    Est") << ", ts=" << std::setprecision(5)
+                stream << (F->isFixed() ? "    Fix" : "    Est") << ", ts=" << std::setprecision(5)
                         << F->getTimeStamp();
-                cout << ",\t x = ( " << std::setprecision(2) << F->getState().transpose() << " )";
-                cout << endl;
+                stream << ",\t x = ( " << std::setprecision(2) << F->getState().transpose() << " )";
+                stream << std::endl;
             }
             if (state_blocks)
             {
-                cout << "    sb:";
+                stream << "    sb:";
                 for (const auto& sb : F->getStateBlockVec())
                 {
-                    cout << " " << (sb->isFixed() ? "Fix" : "Est");
+                    stream << " " << (sb->isFixed() ? "Fix" : "Est");
                 }
-                cout << endl;
+                stream << std::endl;
             }
             if (depth >= 2)
             {
                 // Captures =======================================================================================
                 for (auto C : F->getCaptureList())
                 {
-                    cout << "    Cap" << (C->isMotion() ? "M" : "") << C->id() << " " << C->getType();
+                    stream << "    Cap" << (C->isMotion() ? "M" : "") << C->id() << " " << C->getType();
 
                     if(C->getSensor() != nullptr)
                     {
-                        cout << " -> Sen" << C->getSensor()->id();
+                        stream << " -> Sen" << C->getSensor()->id();
                     }
                     else
-                        cout << " -> S-";
+                        stream << " -> S-";
                     if (C->isMotion())
                     {
                         auto CM = std::static_pointer_cast<CaptureMotion>(C);
                         if (auto OC = CM->getOriginCapture())
                         {
-                            cout << " -> OCap" << OC->id();
+                            stream << " -> OCap" << OC->id();
                             if (auto OF = OC->getFrame())
-                                cout << " ; OFrm" << OF->id();
+                                stream << " ; OFrm" << OF->id();
                         }
                     }
 
-                    cout << ((depth < 3) ? " -- " + std::to_string(C->getFeatureList().size()) + "f" : "");
+                    stream << ((depth < 3) ? " -- " + std::to_string(C->getFeatureList().size()) + "f" : "");
                     if (constr_by)
                     {
-                        cout << "  <-- ";
+                        stream << "  <-- ";
                         for (auto cby : C->getConstrainedByList())
-                            cout << "Fac" << cby->id() << " \t";
+                            stream << "Fac" << cby->id() << " \t";
                     }
-                    cout << endl;
+                    stream << std::endl;
 
                     if (state_blocks)
                         for (const auto& sb : C->getStateBlockVec())
                         {
                             if(sb != nullptr)
                             {
-                                cout << "      sb: ";
-                                cout << (sb->isFixed() ? "Fix" : "Est");
+                                stream << "      sb: ";
+                                stream << (sb->isFixed() ? "Fix" : "Est");
                                 if (metric)
-                                    cout << std::setprecision(2) << " (" << sb->getState().transpose() << " )";
-                                cout << endl;
+                                    stream << std::setprecision(2) << " (" << sb->getState().transpose() << " )";
+                                stream << std::endl;
                             }
                         }
 
                     if (C->isMotion() )
                     {
                         CaptureMotionPtr CM = std::dynamic_pointer_cast<CaptureMotion>(C);
-                        cout << "      buffer size  :  " << CM->getBuffer().get().size() << endl;
+                        stream << "      buffer size  :  " << CM->getBuffer().get().size() << std::endl;
                         if ( metric && ! CM->getBuffer().get().empty())
                         {
-                            cout << "      delta preint : (" << CM->getDeltaPreint().transpose() << ")" << endl;
+                            stream << "      delta preint : (" << CM->getDeltaPreint().transpose() << ")" << std::endl;
                             if (CM->hasCalibration())
                             {
-                                cout << "      calib preint : (" << CM->getCalibrationPreint().transpose() << ")" << endl;
-                                cout << "      jacob preint : (" << CM->getJacobianCalib().row(0) << ")" << endl;
-                                cout << "      calib current: (" << CM->getCalibration().transpose() << ")" << endl;
-                                cout << "      delta correct: (" << CM->getDeltaCorrected(CM->getCalibration()).transpose() << ")" << endl;
+                                stream << "      calib preint : (" << CM->getCalibrationPreint().transpose() << ")" << std::endl;
+                                stream << "      jacob preint : (" << CM->getJacobianCalib().row(0) << ")" << std::endl;
+                                stream << "      calib current: (" << CM->getCalibration().transpose() << ")" << std::endl;
+                                stream << "      delta correct: (" << CM->getDeltaCorrected(CM->getCalibration()).transpose() << ")" << std::endl;
                             }
                         }
                     }
@@ -1058,34 +1056,34 @@ void Problem::print(int depth, bool constr_by, bool metric, bool state_blocks) c
                         // Features =======================================================================================
                         for (auto f : C->getFeatureList())
                         {
-                            cout << "      Ftr" << f->id() << " trk" << f->trackId() << " " << f->getType() << ((depth < 4) ? " -- " + std::to_string(f->getFactorList().size()) + "c  " : "");
+                            stream << "      Ftr" << f->id() << " trk" << f->trackId() << " " << f->getType() << ((depth < 4) ? " -- " + std::to_string(f->getFactorList().size()) + "c  " : "");
                             if (constr_by)
                             {
-                                cout << "  <--\t";
+                                stream << "  <--\t";
                                 for (auto cby : f->getConstrainedByList())
-                                    cout << "Fac" << cby->id() << " \t";
+                                    stream << "Fac" << cby->id() << " \t";
                             }
-                            cout << endl;
+                            stream << std::endl;
                             if (metric)
-                                cout << "        m = ( " << std::setprecision(2) << f->getMeasurement().transpose()
-                                        << " )" << endl;
+                                stream << "        m = ( " << std::setprecision(2) << f->getMeasurement().transpose()
+                                        << " )" << std::endl;
                             if (depth >= 4)
                             {
                                 // Factors =======================================================================================
                                 for (auto c : f->getFactorList())
                                 {
-                                    cout << "        Fac" << c->id() << " " << c->getType() << " -->";
+                                    stream << "        Fac" << c->id() << " " << c->getType() << " -->";
                                     if (c->getFrameOther() == nullptr && c->getCaptureOther() == nullptr && c->getFeatureOther() == nullptr && c->getLandmarkOther() == nullptr)
-                                        cout << " Abs";
+                                        stream << " Abs";
                                     if (c->getFrameOther() != nullptr)
-                                        cout << " Frm" << c->getFrameOther()->id();
+                                        stream << " Frm" << c->getFrameOther()->id();
                                     if (c->getCaptureOther() != nullptr)
-                                        cout << " Cap" << c->getCaptureOther()->id();
+                                        stream << " Cap" << c->getCaptureOther()->id();
                                     if (c->getFeatureOther() != nullptr)
-                                        cout << " Fac" << c->getFeatureOther()->id();
+                                        stream << " Fac" << c->getFeatureOther()->id();
                                     if (c->getLandmarkOther() != nullptr)
-                                        cout << " Lmk" << c->getLandmarkOther()->id();
-                                    cout << endl;
+                                        stream << " Lmk" << c->getLandmarkOther()->id();
+                                    stream << std::endl;
                                 } // for c
                             }
                         } // for f
@@ -1094,320 +1092,62 @@ void Problem::print(int depth, bool constr_by, bool metric, bool state_blocks) c
             }
         } // for F
     }
-    cout << "Map" << ((depth < 1) ? ("        -- " + std::to_string(getMap()->getLandmarkList().size()) + "L") : "") << endl;
+    stream << "Map" << ((depth < 1) ? ("        -- " + std::to_string(getMap()->getLandmarkList().size()) + "L") : "") << std::endl;
     if (depth >= 1)
     {
         // Landmarks =======================================================================================
         for (auto L : getMap()->getLandmarkList())
         {
-            cout << "  Lmk" << L->id() << " " << L->getType();
+            stream << "  Lmk" << L->id() << " " << L->getType();
             if (constr_by)
             {
-                cout << "\t<-- ";
+                stream << "\t<-- ";
                 for (auto cby : L->getConstrainedByList())
-                    cout << "Fac" << cby->id() << " \t";
+                    stream << "Fac" << cby->id() << " \t";
             }
-            cout << endl;
+            stream << std::endl;
             if (metric)
             {
-                cout << (L->isFixed() ? "    Fix" : "    Est");
-                cout << ",\t x = ( " << std::setprecision(2) << L->getState().transpose() << " )";
-                cout << endl;
+                stream << (L->isFixed() ? "    Fix" : "    Est");
+                stream << ",\t x = ( " << std::setprecision(2) << L->getState().transpose() << " )";
+                stream << std::endl;
             }
             if (state_blocks)
             {
-                cout << "    sb:";
+                stream << "    sb:";
                 for (const auto& sb : L->getStateBlockVec())
                 {
                     if (sb != nullptr)
-                        cout << (sb->isFixed() ? " Fix" : " Est");
+                        stream << (sb->isFixed() ? " Fix" : " Est");
                 }
-                cout << endl;
+                stream << std::endl;
             }
         } // for L
     }
-    cout << "-----------------------------------------" << endl;
-    cout << endl;
+    stream << "-----------------------------------------" << std::endl;
+    stream << std::endl;
 }
 
-std::string Problem::printToString(int depth, bool constr_by, bool metric, bool state_blocks) const
-{
-    using std::cout;
-    using std::endl;
-    std::stringstream result;
-
-    result << endl;
-    result << "P: wolf tree status ---------------------" << endl;
-    result << "Hardware" << ((depth < 1) ? ("   -- " + std::to_string(getHardware()->getSensorList().size()) + "S") : "")  << endl;
-    if (depth >= 1)
-    {
-        // Sensors =======================================================================================
-        for (auto S : getHardware()->getSensorList())
-        {
-            result << "  S" << S->id() << " " << S->getType() << " \"" << S->getName() << "\"";
-            if (depth < 2)
-                result << " -- " << S->getProcessorList().size() << "p";
-            result << endl;
-            if (metric && state_blocks)
-            {
-                result << "    sb: ";
-                for (auto& _key : S->getStructure())
-                {
-                    auto key = std::string(1,_key);
-                    auto sb = S->getStateBlock(key);
-                    result << key << "[" << (S->isStateBlockDynamic(key) ? "Dyn" : "Sta") << "," << (sb->isFixed() ? "Fix" : "Est") << "] = ( " << sb->getState().transpose() << " ); ";
-                }
-                result << endl;
-            }
-            else if (metric)
-            {
-                result << "    ( ";
-                for (auto& _key : S->getStructure())
-                {
-                    auto key = std::string(1,_key);
-                    auto sb = S->getStateBlock(key);
-                    result << sb->getState().transpose() << " ";
-                }
-                result << ")" << endl;
-            }
-            else if (state_blocks)
-            {
-                result << "    sb: ";
-                for (auto& _key : S->getStructure())
-                {
-                    auto key = std::string(1,_key);
-                    auto sb = S->getStateBlock(key);
-                    result << key << "[" << (S->isStateBlockDynamic(key) ? "Dyn" : "Sta") << "," << (sb->isFixed() ? "Fix" : "Est") << "]; ";
-                }
-                result << endl;
-            }
-
-
-            if (depth >= 2)
-            {
-                // Processors =======================================================================================
-                for (auto p : S->getProcessorList())
-                {
-                    if (p->isMotion())
-                    {
-                        result << "    pm" << p->id() << " " << p->getType() << " \"" << p->getName() << "\"" << endl;
-                        ProcessorMotionPtr pm = std::static_pointer_cast<ProcessorMotion>(p);
-                        if (pm->getOrigin())
-                            result << "      o: C" << pm->getOrigin()->id() << " - " << (pm->getOrigin()->getFrame()->isKeyOrAux() ? (pm->getOrigin()->getFrame()->isKey() ? "  KF" : "  AuxF" ) : "  F")
-                            << pm->getOrigin()->getFrame()->id() << endl;
-                        if (pm->getLast())
-                            result << "      l: C" << pm->getLast()->id() << " - " << (pm->getLast()->getFrame()->isKeyOrAux() ? (pm->getLast()->getFrame()->isKey() ? "  KF" : " AuxF") : "  F")
-                            << pm->getLast()->getFrame()->id() << endl;
-                        if (pm->getIncoming())
-                            result << "      i: C" << pm->getIncoming()->id() << endl;
-                    }
-                    else
-                    {
-                        result << "    pt" << p->id() << " " << p->getType() << " \"" << p->getName() << "\"" << endl;
-                        ProcessorTrackerPtr pt = std::dynamic_pointer_cast<ProcessorTracker>(p);
-                        if (pt)
-                        {
-                            if (pt->getOrigin())
-                                result << "      o: C" << pt->getOrigin()->id() << " - " << (pt->getOrigin()->getFrame()->isKeyOrAux() ? (pt->getOrigin()->getFrame()->isKey() ? "  KF" : " AuxF") : "  F")
-                                << pt->getOrigin()->getFrame()->id() << endl;
-                            if (pt->getLast())
-                                result << "      l: C" << pt->getLast()->id() << " - " << (pt->getLast()->getFrame()->isKeyOrAux() ? (pt->getLast()->getFrame()->isKey() ? "  KF" : " AuxF") : "  F")
-                                << pt->getLast()->getFrame()->id() << endl;
-                            if (pt->getIncoming())
-                                result << "      i: C" << pt->getIncoming()->id() << endl;
-                        }
-                    }
-                } // for p
-            }
-        } // for S
-    }
-    result << "Trajectory" << ((depth < 1) ? (" -- " + std::to_string(getTrajectory()->getFrameList().size()) + "F") : "")  << endl;
-    if (depth >= 1)
-    {
-        // Frames =======================================================================================
-        for (auto F : getTrajectory()->getFrameList())
-        {
-            result << (F->isKeyOrAux() ? (F->isKey() ? "  KF" : " AuxF") : "  F") << F->id() << ((depth < 2) ? " -- " + std::to_string(F->getCaptureList().size()) + "C  " : "");
-            if (constr_by)
-            {
-                result << "  <-- ";
-                for (auto cby : F->getConstrainedByList())
-                    result << "c" << cby->id() << " \t";
-            }
-            result << endl;
-            if (metric)
-            {
-                result << (F->isFixed() ? "    Fix" : "    Est") << ", ts=" << std::setprecision(5)
-                        << F->getTimeStamp().get();
-                result << ",\t x = ( " << std::setprecision(2) << F->getState().transpose() << " )";
-                result << endl;
-            }
-            if (state_blocks)
-            {
-                result << "    sb:";
-                for (auto sb : F->getStateBlockVec())
-                    if (sb != nullptr)
-                        result << " " << (sb->isFixed() ? "Fix" : "Est");
-                result << endl;
-            }
-            if (depth >= 2)
-            {
-                // Captures =======================================================================================
-                for (auto C : F->getCaptureList())
-                {
-                    result << "    C" << (C->isMotion() ? "M" : "") << C->id() << " " << C->getType();
-
-                    if(C->getSensor() != nullptr)
-                    {
-                        result << " -> S" << C->getSensor()->id();
-                    }
-                    else
-                        result << " -> S-";
-                    if (C->isMotion())
-                    {
-                        auto CM = std::static_pointer_cast<CaptureMotion>(C);
-                        if (auto OC = CM->getOriginCapture())
-                        {
-                            result << " -> OC" << OC->id();
-                            if (auto OF = OC->getFrame())
-                                result << " ; OF" << OF->id();
-                        }
-                    }
-
-                    result << ((depth < 3) ? " -- " + std::to_string(C->getFeatureList().size()) + "f" : "");
-                    if (constr_by)
-                    {
-                        result << "  <-- ";
-                        for (auto cby : C->getConstrainedByList())
-                            result << "c" << cby->id() << " \t";
-                    }
-                    result << endl;
-
-                    if (state_blocks)
-                        for(auto sb : C->getStateBlockVec())
-                            if(sb != nullptr)
-                            {
-                                result << "      sb: ";
-                                result << (sb->isFixed() ? "Fix" : "Est");
-                                if (metric)
-                                    result << std::setprecision(2) << " (" << sb->getState().transpose() << " )";
-                                result << endl;
-                            }
-
-                    if (C->isMotion() )
-                    {
-                        CaptureMotionPtr CM = std::dynamic_pointer_cast<CaptureMotion>(C);
-                        result << "      buffer size  :  " << CM->getBuffer().get().size() << endl;
-                        if ( metric && ! CM->getBuffer().get().empty())
-                        {
-                            result << "      delta preint : (" << CM->getDeltaPreint().transpose() << ")" << endl;
-                            if (CM->hasCalibration())
-                            {
-                                result << "      calib preint : (" << CM->getCalibrationPreint().transpose() << ")" << endl;
-                                result << "      jacob preint : (" << CM->getJacobianCalib().row(0) << ")" << endl;
-                                result << "      calib current: (" << CM->getCalibration().transpose() << ")" << endl;
-                                result << "      delta correct: (" << CM->getDeltaCorrected(CM->getCalibration()).transpose() << ")" << endl;
-                            }
-                        }
-                    }
-
-                    if (depth >= 3)
-                    {
-                        // Features =======================================================================================
-                        for (auto f : C->getFeatureList())
-                        {
-                            result << "      f" << f->id() << " trk" << f->trackId() << " " << f->getType() << ((depth < 4) ? " -- " + std::to_string(f->getFactorList().size()) + "c  " : "");
-                            if (constr_by)
-                            {
-                                result << "  <--\t";
-                                for (auto cby : f->getConstrainedByList())
-                                    result << "c" << cby->id() << " \t";
-                            }
-                            result << endl;
-                            if (metric)
-                                result << "        m = ( " << std::setprecision(2) << f->getMeasurement().transpose()
-                                        << " )" << endl;
-                            if (depth >= 4)
-                            {
-                                // Factors =======================================================================================
-                                for (auto c : f->getFactorList())
-                                {
-                                    result << "        c" << c->id() << " " << c->getType() << " -->";
-                                    if (c->getFrameOther() == nullptr && c->getCaptureOther() == nullptr && c->getFeatureOther() == nullptr && c->getLandmarkOther() == nullptr)
-                                        result << " A";
-                                    if (c->getFrameOther() != nullptr)
-                                        result << " F" << c->getFrameOther()->id();
-                                    if (c->getCaptureOther() != nullptr)
-                                        result << " C" << c->getCaptureOther()->id();
-                                    if (c->getFeatureOther() != nullptr)
-                                        result << " f" << c->getFeatureOther()->id();
-                                    if (c->getLandmarkOther() != nullptr)
-                                        result << " L" << c->getLandmarkOther()->id();
-                                    result << endl;
-                                } // for c
-                            }
-                        } // for f
-                    }
-                } // for C
-            }
-        } // for F
-    }
-    result << "Map" << ((depth < 1) ? ("        -- " + std::to_string(getMap()->getLandmarkList().size()) + "L") : "") << endl;
-    if (depth >= 1)
-    {
-        // Landmarks =======================================================================================
-        for (auto L : getMap()->getLandmarkList())
-        {
-            result << "  L" << L->id() << " " << L->getType();
-            if (constr_by)
-            {
-                result << "\t<-- ";
-                for (auto cby : L->getConstrainedByList())
-                    result << "c" << cby->id() << " \t";
-            }
-            result << endl;
-            if (metric)
-            {
-                result << (L->isFixed() ? "    Fix" : "    Est");
-                result << ",\t x = ( " << std::setprecision(2) << L->getState().transpose() << " )";
-                result << endl;
-            }
-            if (state_blocks)
-            {
-                result << "    sb:";
-                for (auto sb : L->getStateBlockVec())
-                    if (sb != nullptr)
-                        result << (sb->isFixed() ? " Fix" : " Est");
-                result << endl;
-            }
-        } // for L
-    }
-    result << "-----------------------------------------" << endl;
-    result << endl;
-    return result.str();
-}
-bool Problem::check(int verbose_level) const
+bool Problem::check(bool verbose, std::ostream& stream) const
 {
-    using std::cout;
-    using std::endl;
 
     CheckLog log(true, "");
     log.explanation_ = "## WOLF::problem inconsistencies list \n   ---------------------------------- \n";
 
-    if (verbose_level) cout << endl;
-    if (verbose_level) cout << "Wolf tree integrity ---------------------" << endl;
+    if (verbose) stream << std::endl;
+    if (verbose) stream << "Wolf tree integrity ---------------------" << std::endl;
     auto P_raw = this;
-    if (verbose_level > 0)
+    if (verbose)
     {
-        cout << "Prb @ " << P_raw << endl;
+        stream << "Prb @ " << P_raw << std::endl;
     }
     // ------------------------
     //     HARDWARE branch
     // ------------------------
     auto H = hardware_ptr_;
-    if (verbose_level > 0)
+    if (verbose)
     {
-        cout << "Hrw @ " << H.get() << endl;
+        stream << "Hrw @ " << H.get() << std::endl;
     }
     // check pointer to Problem
     // is_consistent = is_consistent && (H->getProblem().get() == P_raw);
@@ -1422,22 +1162,22 @@ bool Problem::check(int verbose_level) const
     // Sensors =======================================================================================
     for (auto S : H->getSensorList())
     {
-        if (verbose_level > 0)
+        if (verbose)
         {
-            cout << "  Sen" << S->id() << " @ " << S.get() << endl;
-            cout << "    -> Prb @ " << S->getProblem().get() << endl;
-            cout << "    -> Hrw @ " << S->getHardware().get() << endl;
+            stream << "  Sen" << S->id() << " @ " << S.get() << std::endl;
+            stream << "    -> Prb @ " << S->getProblem().get() << std::endl;
+            stream << "    -> Hrw @ " << S->getHardware().get() << std::endl;
             for (auto pair: S->getStateBlockMap())
             {
                 auto sb = pair.second;
-                cout <<  "    " << pair.first << " sb @ " << sb.get();
+                stream <<  "    " << pair.first << " sb @ " << sb.get();
                 if (sb)
                 {
                     auto lp = sb->getLocalParametrization();
                     if (lp)
-                        cout <<  " (lp @ " << lp.get() << ")";
+                        stream <<  " (lp @ " << lp.get() << ")";
                 }
-                cout << endl;
+                stream << std::endl;
             }
         }
         // check problem and hardware pointers
@@ -1458,11 +1198,11 @@ bool Problem::check(int verbose_level) const
         //  Processors =======================================================================================
         for (auto p : S->getProcessorList())
         {
-            if (verbose_level > 0)
+            if (verbose)
             {
-                cout << "    Prc" << p->id() << " @ " << p.get() << " -> Sen" << p->getSensor()->id() << endl;
-                cout << "      -> Prb  @ " << p->getProblem().get() << endl;
-                cout << "      -> Sen" << p->getSensor()->id() << " @ " << p->getSensor().get() << endl;
+                stream << "    Prc" << p->id() << " @ " << p.get() << " -> Sen" << p->getSensor()->id() << std::endl;
+                stream << "      -> Prb  @ " << p->getProblem().get() << std::endl;
+                stream << "      -> Sen" << p->getSensor()->id() << " @ " << p->getSensor().get() << std::endl;
             }
             // check problem and sensor pointers
 
@@ -1487,9 +1227,9 @@ bool Problem::check(int verbose_level) const
     //    TRAJECTORY branch
     // ------------------------
     auto T = trajectory_ptr_;
-    if (verbose_level > 0)
+    if (verbose)
     {
-        cout << "Trj @ " << T.get() << endl;
+        stream << "Trj @ " << T.get() << std::endl;
     }
     // check pointer to Problem
     // is_consistent = is_consistent && (T->getProblem().get() == P_raw);
@@ -1504,11 +1244,11 @@ bool Problem::check(int verbose_level) const
     // Frames =======================================================================================
     for (auto F : T->getFrameList())
     {
-      if (verbose_level > 0) {
-        cout << (F->isKeyOrAux() ? (F->isKey() ? "  KFrm" : " EFrm") : "  Frm")
-             << F->id() << " @ " << F.get() << endl;
-        cout << "    -> Prb @ " << F->getProblem().get() << endl;
-        cout << "    -> Trj @ " << F->getTrajectory().get() << endl;
+      if (verbose) {
+        stream << (F->isKeyOrAux() ? (F->isKey() ? "  KFrm" : " EFrm") : "  Frm")
+             << F->id() << " @ " << F.get() << std::endl;
+        stream << "    -> Prb @ " << F->getProblem().get() << std::endl;
+        stream << "    -> Trj @ " << F->getTrajectory().get() << std::endl;
       }
       for (const auto &pair: F->getStateBlockMap()) {
           auto sb = pair.second;
@@ -1519,14 +1259,14 @@ bool Problem::check(int verbose_level) const
               CheckLog((sb.get() != 0), inconsistency_explanation.str()));
           // Clear inconsistency_explanation
           std::stringstream().swap(inconsistency_explanation);
-          if (verbose_level > 0) {
-            cout << "    "<< pair.first << " sb @ " << sb.get();
+          if (verbose) {
+            stream << "    "<< pair.first << " sb @ " << sb.get();
             if (sb) {
               auto lp = sb->getLocalParametrization();
               if (lp)
-                cout << " (lp @ " << lp.get() << ")";
+                stream << " (lp @ " << lp.get() << ")";
             }
-            cout << endl;
+            stream << std::endl;
           }
       }
 
@@ -1558,9 +1298,9 @@ bool Problem::check(int verbose_level) const
             // Clear inconsistency_explanation
             std::stringstream().swap(inconsistency_explanation);
           }
-          if (verbose_level > 0) {
-            cout << "    <- c" << cby->id() << " -> Frm"
-                 << cby->getFrameOther()->id() << endl;
+          if (verbose) {
+            stream << "    <- c" << cby->id() << " -> Frm"
+                 << cby->getFrameOther()->id() << std::endl;
           }
             // check constrained_by pointer to this frame
             // is_consistent = is_consistent && (cby->getFrameOther() == F);
@@ -1574,14 +1314,14 @@ bool Problem::check(int verbose_level) const
             for (auto sb : cby->getStateBlockPtrVector())
             {
 
-              if (verbose_level > 0) {
-                cout << "      sb @ " << sb.get();
+              if (verbose) {
+                stream << "      sb @ " << sb.get();
                 if (sb) {
                   auto lp = sb->getLocalParametrization();
                   if (lp)
-                    cout << " (lp @ " << lp.get() << ")";
+                    stream << " (lp @ " << lp.get() << ")";
                 }
-                cout << endl;
+                stream << std::endl;
               }
             }
         }
@@ -1589,27 +1329,27 @@ bool Problem::check(int verbose_level) const
         // Captures =======================================================================================
         for (auto C : F->getCaptureList())
         {
-            if (verbose_level > 0)
+            if (verbose)
             {
-                cout << "    Cap" << C->id() << " @ " << C.get() << " -> Sen";
-                if (C->getSensor()) cout << C->getSensor()->id();
-                else cout << "-";
-                cout << endl;
-                cout << "      -> Prb  @ " << C->getProblem().get() << endl;
-                cout << "      -> Frm" << C->getFrame()->id() << " @ " << C->getFrame().get() << endl;
+                stream << "    Cap" << C->id() << " @ " << C.get() << " -> Sen";
+                if (C->getSensor()) stream << C->getSensor()->id();
+                else stream << "-";
+                stream << std::endl;
+                stream << "      -> Prb  @ " << C->getProblem().get() << std::endl;
+                stream << "      -> Frm" << C->getFrame()->id() << " @ " << C->getFrame().get() << std::endl;
             }
                 for (auto pair: C->getStateBlockMap())
                 {
                     auto sb = pair.second;
-                    if (verbose_level > 0)
+                    if (verbose)
                     {
-                    cout <<  "      " << pair.first << " sb @ " << sb.get();
+                    stream <<  "      " << pair.first << " sb @ " << sb.get();
                     if (sb) {
                       auto lp = sb->getLocalParametrization();
                       if (lp)
-                        cout << " (lp @ " << lp.get() << ")";
+                        stream << " (lp @ " << lp.get() << ")";
                     }
-                    cout << endl;
+                    stream << std::endl;
                     }
                 }
 
@@ -1633,12 +1373,12 @@ bool Problem::check(int verbose_level) const
             // Features =======================================================================================
             for (auto f : C->getFeatureList())
             {
-                if (verbose_level > 0)
+                if (verbose)
                 {
-                    cout << "      Ftr" << f->id() << " @ " << f.get() << endl;
-                    cout << "        -> Prb  @ " << f->getProblem().get() << endl;
-                    cout << "        -> Cap" << f->getCapture()->id() << " @ " << f->getCapture().get()
-                            << endl;
+                    stream << "      Ftr" << f->id() << " @ " << f.get() << std::endl;
+                    stream << "        -> Prb  @ " << f->getProblem().get() << std::endl;
+                    stream << "        -> Cap" << f->getCapture()->id() << " @ " << f->getCapture().get()
+                            << std::endl;
                 }
                 // check problem and capture pointers
                 // is_consistent = is_consistent && (f->getProblem().get() == P_raw);
@@ -1659,9 +1399,9 @@ bool Problem::check(int verbose_level) const
 
                 for (auto cby : f->getConstrainedByList())
                 {
-                    if (verbose_level > 0)
+                    if (verbose)
                     {
-                        cout << "     <- c" << cby->id() << " -> Ftr" << cby->getFeatureOther()->id() << endl;
+                        stream << "     <- c" << cby->id() << " -> Ftr" << cby->getFeatureOther()->id() << std::endl;
                     }
                     // check constrained_by pointer to this feature
                     // is_consistent = is_consistent && (cby->getFeatureOther() == f);
@@ -1676,8 +1416,8 @@ bool Problem::check(int verbose_level) const
                 // Factors =======================================================================================
                 for (auto c : f->getFactorList())
                 {
-                    if (verbose_level > 0)
-                        cout << "        Fac" << c->id() << " @ " << c.get();
+                    if (verbose)
+                        stream << "        Fac" << c->id() << " @ " << c.get();
 
                     auto Fo = c->getFrameOther();
                     auto Co = c->getCaptureOther();
@@ -1686,24 +1426,24 @@ bool Problem::check(int verbose_level) const
 
                     if ( !Fo && !Co && !fo && !Lo )    // case ABSOLUTE:
                     {
-                        if (verbose_level > 0)
-                            cout << " --> Abs." << endl;
+                        if (verbose)
+                            stream << " --> Abs." << std::endl;
                     }
 
                     // find constrained_by pointer in constrained frame
                     if ( Fo )  // case FRAME:
                     {
-                        if (verbose_level > 0)
-                            cout << " ( --> Frm" << Fo->id() << " <- ";
+                        if (verbose)
+                            stream << " ( --> Frm" << Fo->id() << " <- ";
                         bool found = false;
                         for (auto cby : Fo->getConstrainedByList())
                         {
-                            if (verbose_level > 0)
-                                cout << " Fac" << cby->id();
+                            if (verbose)
+                                stream << " Fac" << cby->id();
                             found = found || (c == cby);
                         }
-                        if (verbose_level > 0)
-                            cout << ")";
+                        if (verbose)
+                            stream << ")";
                         // check constrained_by pointer in constrained frame
                         // is_consistent = is_consistent && found;
 
@@ -1718,17 +1458,17 @@ bool Problem::check(int verbose_level) const
                     // find constrained_by pointer in constrained capture
                     if ( Co )  // case CAPTURE:
                     {
-                        if (verbose_level > 0)
-                            cout << " ( --> Cap" << Co->id() << " <- ";
+                        if (verbose)
+                            stream << " ( --> Cap" << Co->id() << " <- ";
                         bool found = false;
                         for (auto cby : Co->getConstrainedByList())
                         {
-                            if (verbose_level > 0)
-                                cout << " Fac" << cby->id();
+                            if (verbose)
+                                stream << " Fac" << cby->id();
                             found = found || (c == cby);
                         }
-                        if (verbose_level > 0)
-                            cout << ")";
+                        if (verbose)
+                            stream << ")";
                         // check constrained_by pointer in constrained frame
                         // is_consistent = is_consistent && found;
 
@@ -1743,17 +1483,17 @@ bool Problem::check(int verbose_level) const
                     // find constrained_by pointer in constrained feature
                     if ( fo )   // case FEATURE:
                     {
-                        if (verbose_level > 0)
-                            cout << " ( --> Ftr" << fo->id() << " <- ";
+                        if (verbose)
+                            stream << " ( --> Ftr" << fo->id() << " <- ";
                         bool found = false;
                         for (auto cby : fo->getConstrainedByList())
                         {
-                            if (verbose_level > 0)
-                                cout << " Fac" << cby->id();
+                            if (verbose)
+                                stream << " Fac" << cby->id();
                             found = found || (c == cby);
                         }
-                        if (verbose_level > 0)
-                            cout << ")";
+                        if (verbose)
+                            stream << ")";
                         // check constrained_by pointer in constrained feature
                         // is_consistent = is_consistent && found;
 
@@ -1767,17 +1507,17 @@ bool Problem::check(int verbose_level) const
                     // find constrained_by pointer in constrained landmark
                     if ( Lo )      // case LANDMARK:
                     {
-                        if (verbose_level > 0)
-                            cout << " ( --> Lmk" << Lo->id() << " <- ";
+                        if (verbose)
+                            stream << " ( --> Lmk" << Lo->id() << " <- ";
                         bool found = false;
                         for (auto cby : Lo->getConstrainedByList())
                         {
-                            if (verbose_level > 0)
-                                cout << " Fac" << cby->id();
+                            if (verbose)
+                                stream << " Fac" << cby->id();
                             found = found || (c == cby);
                         }
-                        if (verbose_level > 0)
-                            cout << ")";
+                        if (verbose)
+                            stream << ")";
                         // check constrained_by pointer in constrained landmark
                         // is_consistent = is_consistent && found;
 
@@ -1787,13 +1527,13 @@ bool Problem::check(int verbose_level) const
                         //Clear inconsistency_explanation
                         std::stringstream().swap(inconsistency_explanation);
                     }
-                    if (verbose_level > 0)
-                        cout << endl;
+                    if (verbose)
+                        stream << std::endl;
 
-                    if (verbose_level > 0)
+                    if (verbose)
                     {
-                        cout << "          -> Prb  @ " << c->getProblem().get() << endl;
-                        cout << "          -> Ftr" << c->getFeature()->id() << " @ " << c->getFeature().get() << endl;
+                        stream << "          -> Prb  @ " << c->getProblem().get() << std::endl;
+                        stream << "          -> Ftr" << c->getFeature()->id() << " @ " << c->getFeature().get() << std::endl;
                     }
                     // check problem and feature pointers
                     // is_consistent = is_consistent && (c->getProblem().get() == P_raw);
@@ -1817,119 +1557,119 @@ bool Problem::check(int verbose_level) const
                     for (auto sb : c->getStateBlockPtrVector())
                     {
                         bool found = false;
-                        if (verbose_level > 0)
+                        if (verbose)
                         {
-                            cout <<  "          sb @ " << sb.get();
+                            stream <<  "          sb @ " << sb.get();
                             if (sb)
                             {
                                 auto lp = sb->getLocalParametrization();
                                 if (lp)
-                                    cout <<  " (lp @ " << lp.get() << ")";
+                                    stream <<  " (lp @ " << lp.get() << ")";
                             }
                         }
                         bool found_here;
                         std::vector<StateBlockPtr> sb_vec;
 
                         // find in own Frame
-                        sb_vec 		= F->getStateBlockVec();
-                    	found_here 	= (std::find(sb_vec.begin(), sb_vec.end(), sb) != sb_vec.end());
-                        if (found_here) cout << " F" << F->id();
-                        found 		= found || found_here;
+                        sb_vec          = F->getStateBlockVec();
+                        found_here      = (std::find(sb_vec.begin(), sb_vec.end(), sb) != sb_vec.end());
+                        if (found_here) stream << " F" << F->id();
+                        found       = found || found_here;
 
                         // find in own Capture
-                        sb_vec 		= C->getStateBlockVec();
-                    	found_here 	= (std::find(sb_vec.begin(), sb_vec.end(), sb) != sb_vec.end());
-                        if (found_here) cout << " C" << C->id();
-                        found 		= found || found_here;
+                        sb_vec          = C->getStateBlockVec();
+                        found_here      = (std::find(sb_vec.begin(), sb_vec.end(), sb) != sb_vec.end());
+                        if (found_here) stream << " C" << C->id();
+                        found       = found || found_here;
 
                         // Find in other Captures of the own Frame
                         if (!found_here)
-                        	for (auto FC : F->getCaptureList())
-                        	{
-                        		sb_vec 		= FC->getStateBlockVec();
-                        		found_here 	= (std::find(sb_vec.begin(), sb_vec.end(), sb) != sb_vec.end());
-                        		if (found_here) cout << " F" << F->id() << ".C" << FC->id();
-                        		found 		= found || found_here;
-                        	}
+                            for (auto FC : F->getCaptureList())
+                            {
+                                sb_vec          = FC->getStateBlockVec();
+                                found_here      = (std::find(sb_vec.begin(), sb_vec.end(), sb) != sb_vec.end());
+                                if (found_here) stream << " F" << F->id() << ".C" << FC->id();
+                                found       = found || found_here;
+                            }
 
                         // find in own Sensor
                         if (S)
                         {
-                            sb_vec 		= S->getStateBlockVec();
-                        	found_here 	= (std::find(sb_vec.begin(), sb_vec.end(), sb) != sb_vec.end());
-                            if (found_here) cout << " S" << S->id();
-                            found 		= found || found_here;
+                            sb_vec          = S->getStateBlockVec();
+                            found_here      = (std::find(sb_vec.begin(), sb_vec.end(), sb) != sb_vec.end());
+                            if (found_here) stream << " S" << S->id();
+                            found       = found || found_here;
                         }
 
                         // find in constrained Frame
                         if (Fo){
-                        	sb_vec 		= Fo->getStateBlockVec();
-                        	found_here 	= (std::find(sb_vec.begin(), sb_vec.end(), sb) != sb_vec.end());
-                        	if (found_here) cout << " Fo" << Fo->id();
-                            found 		= found || found_here;
+                            sb_vec          = Fo->getStateBlockVec();
+                            found_here      = (std::find(sb_vec.begin(), sb_vec.end(), sb) != sb_vec.end());
+                            if (found_here) stream << " Fo" << Fo->id();
+                            found       = found || found_here;
 
                         }
 
                         // find in constrained Capture
                         if (Co)
                         {
-                        	sb_vec 		= Co->getStateBlockVec();
-                        	found_here 	= (std::find(sb_vec.begin(), sb_vec.end(), sb) != sb_vec.end());
-                            if (found_here) cout << " Co" << Co->id();
-                            found 		= found || found_here;
+                            sb_vec          = Co->getStateBlockVec();
+                            found_here      = (std::find(sb_vec.begin(), sb_vec.end(), sb) != sb_vec.end());
+                            if (found_here) stream << " Co" << Co->id();
+                            found       = found || found_here;
                         }
 
                         // Find in other Captures of the constrained Frame
                         if (!found_here && Fo)
                             for (auto FoC : Fo->getCaptureList())
                             {
-                            	sb_vec 		= FoC->getStateBlockVec();
-                            	found_here 	= (std::find(sb_vec.begin(), sb_vec.end(), sb) != sb_vec.end());
-                            	if (found_here) cout << " Fo" << Fo->id() << ".C" << FoC->id();
-                            	found 		= found || found_here;
+                                sb_vec          = FoC->getStateBlockVec();
+                                found_here      = (std::find(sb_vec.begin(), sb_vec.end(), sb) != sb_vec.end());
+                                if (found_here) stream << " Fo" << Fo->id() << ".C" << FoC->id();
+                                found       = found || found_here;
                             }
 
                         // find in constrained Feature
                         if (fo)
                         {
                             // find in constrained feature's Frame
-                            auto foF 	= fo->getFrame();
-                            sb_vec 		= foF->getStateBlockVec();
-                        	found_here 	= (std::find(sb_vec.begin(), sb_vec.end(), sb) != sb_vec.end());
-                            if (found_here) cout << " foF" << foF->id();
-                            found 		= found || found_here;
+                            auto foF    = fo->getFrame();
+                            sb_vec          = foF->getStateBlockVec();
+                            found_here      = (std::find(sb_vec.begin(), sb_vec.end(), sb) != sb_vec.end());
+                            if (found_here) stream << " foF" << foF->id();
+                            found       = found || found_here;
 
                             // find in constrained feature's Capture
-                            auto foC 	= fo->getCapture();
-                            sb_vec 		= foC->getStateBlockVec();
-                        	found_here 	= (std::find(sb_vec.begin(), sb_vec.end(), sb) != sb_vec.end());
-                            if (found_here) cout << " foC" << foC->id();
-                            found 		= found || found_here;
+                            auto foC    = fo->getCapture();
+                            sb_vec          = foC->getStateBlockVec();
+                            found_here      = (std::find(sb_vec.begin(), sb_vec.end(), sb) != sb_vec.end());
+                            if (found_here) stream << " foC" << foC->id();
+                            found       = found || found_here;
 
                             // find in constrained feature's Sensor
-                            auto foS 	= fo->getCapture()->getSensor();
-                            sb_vec 		= foS->getStateBlockVec();
-                        	found_here 	= (std::find(sb_vec.begin(), sb_vec.end(), sb) != sb_vec.end());
-                            if (found_here) cout << " foS" << foS->id();
-                            found 		= found || found_here;
+                            auto foS    = fo->getCapture()->getSensor();
+                            sb_vec          = foS->getStateBlockVec();
+                            found_here      = (std::find(sb_vec.begin(), sb_vec.end(), sb) != sb_vec.end());
+                            if (found_here) stream << " foS" << foS->id();
+                            found       = found || found_here;
                         }
 
                         // find in constrained landmark
                         if (Lo)
                         {
-                        	sb_vec 		= Lo->getStateBlockVec();
-                        	found_here 	= (std::find(sb_vec.begin(), sb_vec.end(), sb) != sb_vec.end());
-                            if (found_here) cout << " Lo" << Lo->id();
-                            found 		= found || found_here;
+                            sb_vec          = Lo->getStateBlockVec();
+                            found_here      = (std::find(sb_vec.begin(), sb_vec.end(), sb) != sb_vec.end());
+                            if (found_here) stream << " Lo" << Lo->id();
+                            found       = found || found_here;
                         }
 
-                        if (verbose_level > 0)
+                        if (verbose)
                         {
                             if (found)
-                                cout << " found";
+                                stream << " found";
                             else
-                                cout << " NOT FOUND !";
-                            cout << endl;
+                                stream << " NOT FOUND !";
+                            stream << std::endl;
                         }
 
                         inconsistency_explanation << "The stateblock " << sb << " has not been found (is floating!)";
@@ -1953,8 +1693,8 @@ bool Problem::check(int verbose_level) const
     //       MAP branch
     // ------------------------
     auto M = map_ptr_;
-    if (verbose_level > 0)
-        cout << "Map @ " << M.get() << endl;
+    if (verbose)
+        stream << "Map @ " << M.get() << std::endl;
     // check pointer to Problem
     // is_consistent = is_consistent && (M->getProblem().get() == P_raw);
 
@@ -1966,22 +1706,22 @@ bool Problem::check(int verbose_level) const
     // Landmarks =======================================================================================
     for (auto L : M->getLandmarkList())
     {
-        if (verbose_level > 0)
+        if (verbose)
         {
-            cout << "  Lmk" << L->id() << " @ " << L.get() << endl;
-            cout << "  -> Prb @ " << L->getProblem().get() << endl;
-            cout << "  -> Map @ " << L->getMap().get() << endl;
+            stream << "  Lmk" << L->id() << " @ " << L.get() << std::endl;
+            stream << "  -> Prb @ " << L->getProblem().get() << std::endl;
+            stream << "  -> Map @ " << L->getMap().get() << std::endl;
             for (const auto& pair : L->getStateBlockMap())
             {
                 auto sb = pair.second;
-                cout <<  "  " << pair.first << " sb @ " << sb.get();
+                stream <<  "  " << pair.first << " sb @ " << sb.get();
                 if (sb)
                 {
                     auto lp = sb->getLocalParametrization();
                     if (lp)
-                        cout <<  " (lp @ " << lp.get() << ")";
+                        stream <<  " (lp @ " << lp.get() << ")";
                 }
-                cout << endl;
+                stream << std::endl;
             }
         }
         // check problem and map pointers
@@ -2005,9 +1745,9 @@ bool Problem::check(int verbose_level) const
         std::stringstream().swap(inconsistency_explanation);
 
         for (auto cby : L->getConstrainedByList()) {
-          if (verbose_level > 0)
-            cout << "      <- Fac" << cby->id() << " -> Lmk"
-                 << cby->getLandmarkOther()->id() << endl;
+          if (verbose)
+            stream << "      <- Fac" << cby->id() << " -> Lmk"
+                 << cby->getLandmarkOther()->id() << std::endl;
           // check constrained_by pointer to this landmark
           // is_consistent =
               // is_consistent && (cby->getLandmarkOther() &&
@@ -2022,26 +1762,34 @@ bool Problem::check(int verbose_level) const
           std::stringstream().swap(inconsistency_explanation);
 
           for (auto sb : cby->getStateBlockPtrVector()) {
-            if (verbose_level > 0) {
-              cout << "      sb @ " << sb.get();
+            if (verbose) {
+              stream << "      sb @ " << sb.get();
               if (sb) {
                 auto lp = sb->getLocalParametrization();
                 if (lp)
-                  cout << " (lp @ " << lp.get() << ")";
+                  stream << " (lp @ " << lp.get() << ")";
               }
-              cout << endl;
+              stream << std::endl;
             }
           }
         }
     }
 
-    if (verbose_level) cout << "--------------------------- Wolf tree " << (log.is_consistent_ ? " OK" : "Not OK !!") << endl;
-    if (verbose_level) cout << endl;
-    if (verbose_level and not log.is_consistent_) cout << log.explanation_ << endl;
+    if (verbose) stream << "--------------------------- Wolf tree " << (log.is_consistent_ ? " OK" : "Not OK !!") << std::endl;
+    if (verbose) stream << std::endl;
+    if (verbose and not log.is_consistent_) stream << log.explanation_ << std::endl;
 
     return log.is_consistent_;
 }
 
+bool Problem::check(int verbose_level) const
+{
+    return check((verbose_level > 0), std::cout);
+}
+void Problem::print(int depth, bool constr_by, bool metric, bool state_blocks) const
+{
+    print(depth, std::cout, constr_by, metric, state_blocks);
+}
 void Problem::print(const std::string& depth, bool constr_by, bool metric, bool state_blocks) const
 {
     if (depth.compare("T") == 0)