diff --git a/lightsim2grid/gridmodel/from_pypowsybl.py b/lightsim2grid/gridmodel/from_pypowsybl.py
index 375fa9d..b82a269 100644
--- a/lightsim2grid/gridmodel/from_pypowsybl.py
+++ b/lightsim2grid/gridmodel/from_pypowsybl.py
@@ -30,7 +30,7 @@ def _aux_get_bus(bus_df, df, conn_key="connected", bus_key="bus_id"):
     # mask_disco[wrong_component] = True
     # assign bus -1 to disconnected elements
     bus_id[mask_disco] = -1
-    return bus_id , mask_disco.values
+    return bus_id, mask_disco.values
 
 
 def init(net : pypo.network,
diff --git a/lightsim2grid/securityAnalysis.py b/lightsim2grid/securityAnalysis.py
index aa555ab..a0cc724 100644
--- a/lightsim2grid/securityAnalysis.py
+++ b/lightsim2grid/securityAnalysis.py
@@ -8,8 +8,6 @@
 
 __all__ = ["SecurityAnalysisCPP", "SecurityAnalysis"]
 
-import os
-import warnings
 import copy
 import numpy as np
 from collections.abc import Iterable
diff --git a/src/BaseSolver.h b/src/BaseSolver.h
index 54d8710..8c1eaba 100644
--- a/src/BaseSolver.h
+++ b/src/BaseSolver.h
@@ -98,6 +98,16 @@ class BaseSolver : public BaseConstants
                         real_type tol
                         ) = 0 ;
 
+        virtual Eigen::SparseMatrix<real_type> get_ptdf(){
+            throw std::runtime_error("Impossible to get the PTDF matrix with this solver type.");
+        }
+        virtual Eigen::SparseMatrix<real_type> get_lodf(){  // TODO interface is likely to change
+            throw std::runtime_error("Impossible to get the LODF matrix with this solver type.");
+        }
+        virtual Eigen::SparseMatrix<real_type> get_bsdf(){  // TODO interface is likely to change
+            throw std::runtime_error("Impossible to get the BSDF matrix with this solver type.");
+        }
+
         virtual
         void reset();
         
diff --git a/src/ChooseSolver.h b/src/ChooseSolver.h
index 57d5e69..ce75188 100644
--- a/src/ChooseSolver.h
+++ b/src/ChooseSolver.h
@@ -218,6 +218,7 @@ class ChooseSolver
             auto p_solver = get_prt_solver("get_Vm", true);
             return p_solver -> get_Vm();
         }
+
         Eigen::Ref<const Eigen::SparseMatrix<real_type> > get_J() const
         {
             check_right_solver("get_J");
@@ -262,6 +263,18 @@ class ChooseSolver
             else throw std::runtime_error("Unknown solver type encountered (get_J)");
         }
 
+        Eigen::SparseMatrix<real_type> get_ptdf(){
+                if(_solver_type != SolverType::DC && 
+                    _solver_type != SolverType::KLUDC && 
+                    _solver_type != SolverType::NICSLUDC &&
+                    _solver_type != SolverType::CKTSODC){
+                throw std::runtime_error("ChooseSolver::get_ptdf: cannot get ptdf for a solver that is not DC.");
+                }
+            auto p_solver = get_prt_solver("get_ptdf", true);
+            const auto & res =  p_solver -> get_ptdf();
+            return res;
+        }
+
         /** apparently i cannot pass a const ref for a sparse matrix in python**/
         Eigen::SparseMatrix<real_type> get_J_python() const{
             Eigen::SparseMatrix<real_type> res = get_J();
diff --git a/src/DCSolver.h b/src/DCSolver.h
index 54e1657..e8ee780 100644
--- a/src/DCSolver.h
+++ b/src/DCSolver.h
@@ -34,6 +34,10 @@ class BaseDCSolver: public BaseSolver
                         real_type tol
                         );
 
+        virtual Eigen::SparseMatrix<real_type> get_ptdf();  // TODO
+        virtual Eigen::SparseMatrix<real_type> get_lodf();  // TODO
+        virtual Eigen::SparseMatrix<real_type> get_bsdf();  // TODO
+
     private:
         // no copy allowed
         BaseDCSolver( const BaseSolver & ) =delete ;
@@ -42,6 +46,8 @@ class BaseDCSolver: public BaseSolver
     protected:
         LinearSolver  _linear_solver;
         bool need_factorize_;
+        RealVect Sbus_noslack_;
+        Eigen::SparseMatrix<real_type> Ybus_noslack_;
 
 };
 
diff --git a/src/DCSolver.tpp b/src/DCSolver.tpp
index 36611ee..114f76c 100644
--- a/src/DCSolver.tpp
+++ b/src/DCSolver.tpp
@@ -169,3 +169,25 @@ void BaseDCSolver<LinearSolver>::reset(){
     _linear_solver.reset();
     need_factorize_ = true;
 }
+
+template<class LinearSolver>
+Eigen::SparseMatrix<real_type> BaseDCSolver<LinearSolver>::get_ptdf(){
+    // TODO
+    // Bf (nb_branch, nb_bus) : en dc un truc du genre 1 / x / tap for (1..nb_branch, from_bus)
+    // and -1. / x / tap for (1..nb_branch, to_bus) 
+    return Ybus_noslack_;
+}
+
+template<class LinearSolver>
+Eigen::SparseMatrix<real_type> BaseDCSolver<LinearSolver>::get_lodf(){
+    // TODO
+    return Ybus_noslack_;
+
+}
+
+template<class LinearSolver>
+Eigen::SparseMatrix<real_type> BaseDCSolver<LinearSolver>::get_bsdf(){
+    // TODO
+    return Ybus_noslack_;
+
+}
diff --git a/src/GridModel.cpp b/src/GridModel.cpp
index e8fbc75..0c13b70 100644
--- a/src/GridModel.cpp
+++ b/src/GridModel.cpp
@@ -720,6 +720,13 @@ CplxVect GridModel::dc_pf(const CplxVect & Vinit,
     return res;
 }
 
+Eigen::SparseMatrix<real_type> GridModel::get_ptdf(){
+    if(Ybus_dc_.size() == 0){
+        throw std::runtime_error("Cannot get the ptdf without having first computed a dc powerflow.");
+    }
+    return _dc_solver.get_ptdf();
+}
+
 /**
 Retrieve the number of connected buses
 **/
diff --git a/src/GridModel.h b/src/GridModel.h
index a4d31b8..4df9ee1 100644
--- a/src/GridModel.h
+++ b/src/GridModel.h
@@ -267,6 +267,7 @@ class GridModel : public DataGeneric
                        int max_iter,  // not used for DC
                        real_type tol  // not used for DC
                        );
+        Eigen::SparseMatrix<real_type> get_ptdf();
 
         // ac powerflow
         CplxVect ac_pf(const CplxVect & Vinit,