alxbilger · Sep 28, 2026 · Sep 28, 2026 · Sep 28, 2026 · Sep 28, 2026 · Sep 28, 2026
diff --git a/Sofa/Component/Mass/Testing/src/sofa/component/mass/testing/MassTestCreation.h b/Sofa/Component/Mass/Testing/src/sofa/component/mass/testing/MassTestCreation.h
@@ -77,7 +77,7 @@ struct Mass_test : public sofa::testing::BaseSimulationTest, public sofa::testin
     bool m_debug;           ///< Print debug messages. Default is false.
     /// }
 
-    bool m_testAccFromF { true };
+    bool m_testSolveLinearSystem { true };
     bool m_testAddMToMatrix { true };
     bool m_testBuildMassMatrix { true };
     bool m_testKineticEnergy { true };
@@ -238,11 +238,11 @@ struct Mass_test : public sofa::testing::BaseSimulationTest, public sofa::testin
             checkKineticEnergy(v, n, mparams, Mv);
         }
 
-        // 2. Test accFromF: a = M^-1 * f
+        // 2. Test solveLinearSystem: a = M^-1 * f
         // a = M^-1 * (M * v) should be v
-        if (m_testAccFromF)
+        if (m_testSolveLinearSystem)
         {
-            m_mass->accFromF(&mparams, sofa::core::vec_id::write_access::force);
+            m_mass->solveLinearSystem(&mparams, sofa::core::vec_id::write_access::force, sofa::core::vec_id::read_access::force);
 
             VecDeriv a;
             sofa::testing::copyFromData(a, m_dof->readForces());
@@ -251,7 +251,7 @@ struct Mass_test : public sofa::testing::BaseSimulationTest, public sofa::testin
                 * std::max((SReal)1, (SReal)this->vectorMaxAbs(v));
 
             EXPECT_LT((SReal)this->vectorMaxDiff(a, v), tolerance)
-                << "accFromF inconsistent with addMDx (M^-1 * M * v != v)";
+                << "solveLinearSystem inconsistent with addMDx (M^-1 * M * v != v)";
         }
 
         sofa::SignedIndex matrixSize = (sofa::SignedIndex)(n * DataTypes::deriv_total_size);

diff --git a/Sofa/Component/Mass/src/sofa/component/mass/DiagonalMass.h b/Sofa/Component/Mass/src/sofa/component/mass/DiagonalMass.h
@@ -293,7 +293,7 @@ class DiagonalMass : public core::behavior::Mass<DataTypes>, public virtual sofa
     // -- Mass interface
     void addMDx(const core::MechanicalParams* mparams, DataVecDeriv& f, const DataVecDeriv& dx, SReal factor) override;
 
-    void accFromF(const core::MechanicalParams* mparams, DataVecDeriv& a, const DataVecDeriv& f) override;
+    void doSolveLinearSystem(const core::MechanicalParams* mparams, DataVecDeriv& a, const DataVecDeriv& f) override;
 
     void addForce(const core::MechanicalParams* mparams, DataVecDeriv& f, const DataVecCoord& x, const DataVecDeriv& v) override;
 

diff --git a/Sofa/Component/Mass/src/sofa/component/mass/DiagonalMass.inl b/Sofa/Component/Mass/src/sofa/component/mass/DiagonalMass.inl
@@ -561,7 +561,7 @@ void DiagonalMass<DataTypes, GeometricalTypes>::addMDx(const core::MechanicalPar
 
 
 template <class DataTypes, class GeometricalTypes>
-void DiagonalMass<DataTypes, GeometricalTypes>::accFromF(const core::MechanicalParams* /*mparams*/, DataVecDeriv& a, const DataVecDeriv& f)
+void DiagonalMass<DataTypes, GeometricalTypes>::doSolveLinearSystem(const core::MechanicalParams* /*mparams*/, DataVecDeriv& a, const DataVecDeriv& f)
 {
 
     const MassVector &masses= d_vertexMass.getValue();

diff --git a/Sofa/Component/Mass/src/sofa/component/mass/FEMMass.h b/Sofa/Component/Mass/src/sofa/component/mass/FEMMass.h
@@ -148,15 +148,14 @@ class FEMMass :
      */
     void addMDx(const core::MechanicalParams* mparams, DataVecDeriv_t<DataTypes>& f, const DataVecDeriv_t<DataTypes>& dx, SReal factor) override;
 
-    using Inherit1::accFromF;
     /**
      * @brief Compute $ a = M^{-1} f $ if the mass matrix is lumped. Triggers an error otherwise.
      *
      * @param mparams Mechanical parameters for the computation.
      * @param a The result vector of $M^{-1} f$.
      * @param f The vector to be multiplied by the inverse mass matrix.
      */
-    void accFromF(const core::MechanicalParams* mparams, DataVecDeriv_t<DataTypes>& a, const DataVecDeriv_t<DataTypes>& f) override;
+    void doSolveLinearSystem(const core::MechanicalParams* mparams, DataVecDeriv_t<DataTypes>& a, const DataVecDeriv_t<DataTypes>& f) override;
 
 
     using Inherit1::getKineticEnergy;

diff --git a/Sofa/Component/Mass/src/sofa/component/mass/FEMMass.inl b/Sofa/Component/Mass/src/sofa/component/mass/FEMMass.inl
@@ -299,7 +299,7 @@ void FEMMass<TDataTypes, TElementType>::addMDx(const core::MechanicalParams* mpa
 }
 
 template <class TDataTypes, class TElementType>
-void FEMMass<TDataTypes, TElementType>::accFromF(const core::MechanicalParams* mparams,
+void FEMMass<TDataTypes, TElementType>::doSolveLinearSystem(const core::MechanicalParams* mparams,
                                                         DataVecDeriv_t<DataTypes>& a,
                                                         const DataVecDeriv_t<DataTypes>& f)
 {
@@ -310,7 +310,7 @@ void FEMMass<TDataTypes, TElementType>::accFromF(const core::MechanicalParams* m
 
     if (!d_lumping.getValue())
     {
-        msg_error() << "the method 'accFromF' can't be used with this component as this "
+        msg_error() << "the method 'solveLinearSystem' can't be used with this component as this "
                         "SPARSE mass matrix can't be inversed easily. Enable 'lumping' instead.";
         return;
     }

diff --git a/Sofa/Component/Mass/src/sofa/component/mass/MeshMatrixMass.h b/Sofa/Component/Mass/src/sofa/component/mass/MeshMatrixMass.h
@@ -200,8 +200,7 @@ class MeshMatrixMass : public core::behavior::Mass<DataTypes>, public virtual co
     using Inherited::addMDx;
     void addMDx(const core::MechanicalParams*, DataVecDeriv& f, const DataVecDeriv& dx, SReal factor) override;
 
-    using Inherited::accFromF;
-    void accFromF(const core::MechanicalParams*, DataVecDeriv& a, const DataVecDeriv& f) override; // This function can't be used as it use M^-1
+    void doSolveLinearSystem(const core::MechanicalParams*, DataVecDeriv& a, const DataVecDeriv& f) override; // This function can't be used as it use M^-1
 
     void addForce(const core::MechanicalParams*, DataVecDeriv& f, const DataVecCoord& x, const DataVecDeriv& v) override;
 

diff --git a/Sofa/Component/Mass/src/sofa/component/mass/MeshMatrixMass.inl b/Sofa/Component/Mass/src/sofa/component/mass/MeshMatrixMass.inl
@@ -2048,12 +2048,12 @@ void MeshMatrixMass<DataTypes, GeometricalTypes>::addMDx(const core::MechanicalP
 
 
 template <class DataTypes, class GeometricalTypes>
-void MeshMatrixMass<DataTypes, GeometricalTypes>::accFromF(const core::MechanicalParams* mparams, DataVecDeriv& a, const DataVecDeriv& f)
+void MeshMatrixMass<DataTypes, GeometricalTypes>::doSolveLinearSystem(const core::MechanicalParams* mparams, DataVecDeriv& a, const DataVecDeriv& f)
 {
     SOFA_UNUSED(mparams);
     if( !isLumped() )
     {
-        msg_error() << "the method 'accFromF' can't be used with MeshMatrixMass as this SPARSE mass matrix can't be inversed easily. "
+        msg_error() << "the method 'solveLinearSystem' can't be used with MeshMatrixMass as this SPARSE mass matrix can't be inversed easily. "
                     << "Please proceed to mass lumping or use a DiagonalMass (both are equivalent).";
         return;
     }

diff --git a/Sofa/Component/Mass/src/sofa/component/mass/UniformMass.h b/Sofa/Component/Mass/src/sofa/component/mass/UniformMass.h
@@ -131,8 +131,7 @@ class UniformMass : public core::behavior::Mass<DataTypes>, public virtual core:
 
     using Inherited::addMDx;
     void addMDx(const core::MechanicalParams* mparams, DataVecDeriv& f, const DataVecDeriv& dx, SReal factor) override;
-    using Inherited::accFromF;
-    void accFromF(const core::MechanicalParams* mparams, DataVecDeriv& a, const DataVecDeriv& f) override;
+    void doSolveLinearSystem(const core::MechanicalParams* mparams, DataVecDeriv& a, const DataVecDeriv& f) override;
     void addForce(const core::MechanicalParams* mparams, DataVecDeriv& f, const DataVecCoord& x, const DataVecDeriv& v) override;
 
     using Inherited::getKineticEnergy;

diff --git a/Sofa/Component/Mass/src/sofa/component/mass/UniformMass.inl b/Sofa/Component/Mass/src/sofa/component/mass/UniformMass.inl
@@ -420,7 +420,7 @@ void UniformMass<DataTypes>::addMDx ( const core::MechanicalParams*, DataVecDeri
 
 
 template <class DataTypes>
-void UniformMass<DataTypes>::accFromF ( const core::MechanicalParams*, DataVecDeriv& va, const DataVecDeriv& vf )
+void UniformMass<DataTypes>::doSolveLinearSystem ( const core::MechanicalParams*, DataVecDeriv& va, const DataVecDeriv& vf )
 {
     if (!this->isComponentStateValid())
         return;

diff --git a/Sofa/Component/Mass/tests/MassTestCreation[FEMMass].cpp b/Sofa/Component/Mass/tests/MassTestCreation[FEMMass].cpp
@@ -46,7 +46,7 @@ struct ElementMass_template_test : public Mass_test<FEMMass<typename MassParam::
 
     ElementMass_template_test()
     {
-        this->m_testAccFromF = false;
+        this->m_testSolveLinearSystem = false;
         this->m_testAddMToMatrix = false;
         this->m_errorMax = 1e2_sreal;
 

diff --git a/Sofa/Component/Mass/tests/MassTestCreation[MeshMatrixMass].cpp b/Sofa/Component/Mass/tests/MassTestCreation[MeshMatrixMass].cpp
@@ -64,7 +64,7 @@ struct MeshMatrixMass_template_test : public Mass_test<MeshMatrixMass<DataTypes>
 
         m_topology->computeCrossElementBuffers();
 
-        this->m_testAccFromF = lumped;
+        this->m_testSolveLinearSystem = lumped;
         this->m_mass->d_lumping.setValue(lumped);
 
         this->run_test(x, v);

diff --git a/...EM/Elastic/src/sofa/component/solidmechanics/fem/elastic/HexahedralFEMForceFieldAndMass.h b/...EM/Elastic/src/sofa/component/solidmechanics/fem/elastic/HexahedralFEMForceFieldAndMass.h
@@ -82,7 +82,7 @@ class HexahedralFEMForceFieldAndMass : virtual public sofa::core::behavior::Mass
     ///// WARNING this method only add diagonal elements in the given matrix !
     void addMBKToMatrix(const core::MechanicalParams* mparams, const sofa::core::behavior::MultiMatrixAccessor* matrix) override;
 
-     void accFromF(const core::MechanicalParams* mparams, DataVecDeriv& a, const DataVecDeriv& f) override;
+     void doSolveLinearSystem(const core::MechanicalParams* mparams, DataVecDeriv& a, const DataVecDeriv& f) override;
 
      void addForce(const core::MechanicalParams* mparams, DataVecDeriv& f, const DataVecCoord& x, const DataVecDeriv& v) override;
 

diff --git a/.../Elastic/src/sofa/component/solidmechanics/fem/elastic/HexahedralFEMForceFieldAndMass.inl b/.../Elastic/src/sofa/component/solidmechanics/fem/elastic/HexahedralFEMForceFieldAndMass.inl
@@ -385,9 +385,9 @@ void HexahedralFEMForceFieldAndMass<DataTypes>::addMBKToMatrix (const core::Mech
 
 
 template<class DataTypes>
-void HexahedralFEMForceFieldAndMass<DataTypes>::accFromF(const core::MechanicalParams*, DataVecDeriv& /*a*/, const DataVecDeriv& /*f*/)
+void HexahedralFEMForceFieldAndMass<DataTypes>::doSolveLinearSystem(const core::MechanicalParams*, DataVecDeriv& /*a*/, const DataVecDeriv& /*f*/)
 {
-    msg_error() << "HexahedralFEMForceFieldAndMass<DataTypes>::accFromF not yet implemented";
+    msg_error() << "HexahedralFEMForceFieldAndMass<DataTypes>::solveLinearSystem not yet implemented";
     // need to built the big global mass matrix and to inverse it...
 }
 

diff --git a/...EM/Elastic/src/sofa/component/solidmechanics/fem/elastic/HexahedronFEMForceFieldAndMass.h b/...EM/Elastic/src/sofa/component/solidmechanics/fem/elastic/HexahedronFEMForceFieldAndMass.h
@@ -87,7 +87,7 @@ class HexahedronFEMForceFieldAndMass : virtual public core::behavior::Mass<DataT
     void buildStiffnessMatrix(core::behavior::StiffnessMatrix*) override;
     void buildMassMatrix(sofa::core::behavior::MassMatrixAccumulator* matrices) override;
 
-     void accFromF(const core::MechanicalParams* mparams, DataVecDeriv& a, const DataVecDeriv& f) override;
+     void doSolveLinearSystem(const core::MechanicalParams* mparams, DataVecDeriv& a, const DataVecDeriv& f) override;
 
      void addForce(const core::MechanicalParams* mparams, DataVecDeriv& f, const DataVecCoord& x, const DataVecDeriv& v) override;
 

diff --git a/.../Elastic/src/sofa/component/solidmechanics/fem/elastic/HexahedronFEMForceFieldAndMass.inl b/.../Elastic/src/sofa/component/solidmechanics/fem/elastic/HexahedronFEMForceFieldAndMass.inl
@@ -289,9 +289,9 @@ void HexahedronFEMForceFieldAndMass<DataTypes>::buildMassMatrix(sofa::core::beha
 }
 
 template<class DataTypes>
-void HexahedronFEMForceFieldAndMass<DataTypes>::accFromF(const core::MechanicalParams* /*mparams*/, DataVecDeriv& /*a*/, const DataVecDeriv& /*f*/)
+void HexahedronFEMForceFieldAndMass<DataTypes>::doSolveLinearSystem(const core::MechanicalParams* /*mparams*/, DataVecDeriv& /*a*/, const DataVecDeriv& /*f*/)
 {
-    msg_warning()<<"HexahedronFEMForceFieldAndMass<DataTypes>::accFromF not yet implemented"<<msgendl;
+    msg_warning()<<"HexahedronFEMForceFieldAndMass<DataTypes>::solveLinearSystem not yet implemented"<<msgendl;
     // need to built the big global mass matrix and to inverse it...
 }
 

diff --git a/Sofa/framework/Core/src/sofa/core/behavior/BaseMass.cpp b/Sofa/framework/Core/src/sofa/core/behavior/BaseMass.cpp
@@ -54,6 +54,11 @@ SReal BaseMass::getPotentialEnergy(const MechanicalParams* mparams) const
     return this->getPotentialEnergy(mparams, mparams->x());
 }
 
+void BaseMass::accFromF(const MechanicalParams* mparams, MultiVecDerivId aid)
+{
+    solveLinearSystem(mparams, aid, mparams->f());
+}
+
 void BaseMass::buildMassMatrix(sofa::core::behavior::MassMatrixAccumulator* matrices)
 {
     static std::set<BaseMass*> hasEmittedWarning;

diff --git a/Sofa/framework/Core/src/sofa/core/behavior/BaseMass.h b/Sofa/framework/Core/src/sofa/core/behavior/BaseMass.h
@@ -62,7 +62,15 @@ class SOFA_CORE_API BaseMass : public virtual StateAccessor
     virtual void addMDx(const MechanicalParams* mparams, MultiVecDerivId fid, SReal factor) =0;
 
     /// dx = M^-1 f
-    virtual void accFromF(const MechanicalParams* mparams, MultiVecDerivId aid) = 0;
+    SOFA_CORE_DEPRECATED_ACCFROMF()
+    virtual void accFromF(const MechanicalParams* mparams, MultiVecDerivId aid) final;
+
+    /// Solve M x = b, or x = M^-1 b, where M is the mass matrix
+    ///
+    /// Warning: this method is only implemented in derived classes when the mass matrix is trivial
+    /// (for example, diagonal mass matrices), allowing for efficient linear system solving. In the
+    /// other cases, it may be necessary to use a more general linear solver.
+    virtual void solveLinearSystem(const MechanicalParams* mparams, MultiVecDerivId xId, ConstMultiVecDerivId bId) = 0;
 
     /// \brief Perform  v += dt*g operation. Used if mass wants to added G separately from the other forces to v.
     ///

diff --git a/Sofa/framework/Core/src/sofa/core/behavior/Mass.h b/Sofa/framework/Core/src/sofa/core/behavior/Mass.h
@@ -68,14 +68,11 @@ class Mass : virtual public ForceField<DataTypes>, public BaseMass
 
     virtual void addMDx(const MechanicalParams* mparams, DataVecDeriv& f, const DataVecDeriv& dx, SReal factor);
 
-    ///                            $ dx = M^-1 f $
-    ///
-    /// This method retrieves the force and dx vector and call the internal
-    /// accFromF(VecDeriv&,const VecDeriv&) method implemented by the component.
-    void accFromF(const MechanicalParams* mparams, MultiVecDerivId aid) override;
-
+    SOFA_CORE_DEPRECATED_ACCFROMF()
     virtual void accFromF(const MechanicalParams* mparams, DataVecDeriv& a, const DataVecDeriv& f);
 
+    void solveLinearSystem(const MechanicalParams* mparams, MultiVecDerivId xId, ConstMultiVecDerivId bId) override;
+    virtual void doSolveLinearSystem(const MechanicalParams* mparams, DataVecDeriv& x, const DataVecDeriv& b);
 
     /// Mass forces (gravity) often have null derivative
     void addDForce(const MechanicalParams* /*mparams*/, DataVecDeriv & /*df*/, const DataVecDeriv & /*dx*/ ) override;

diff --git a/Sofa/framework/Core/src/sofa/core/behavior/Mass.inl b/Sofa/framework/Core/src/sofa/core/behavior/Mass.inl
@@ -64,26 +64,40 @@ void Mass<DataTypes>::addMDx(const MechanicalParams* /*mparams*/, DataVecDeriv&
     msg_warning() << "Method addMDx(const MechanicalParams* , DataVecDeriv& , const DataVecDeriv&  , SReal  ) not implemented.";
 }
 
-
 template<class DataTypes>
-void Mass<DataTypes>::accFromF(const MechanicalParams* mparams, MultiVecDerivId aid)
+void Mass<DataTypes>::accFromF(const MechanicalParams* /*mparams*/, DataVecDeriv& /*a*/, const DataVecDeriv& /*f*/)
+{
+    msg_warning() << "Method accFromF(const MechanicalParams* , DataVecDeriv& , const DataVecDeriv& ) not implemented.";
+}
+
+template <class DataTypes>
+void Mass<DataTypes>::solveLinearSystem(const MechanicalParams* mparams,
+    MultiVecDerivId xId, ConstMultiVecDerivId bId)
 {
     if(mparams)
     {
         auto mstate = this->mstate.get();
-        accFromF(mparams, *aid[mstate].write(), *mparams->readF(mstate));
+
+        DataVecDeriv* x = xId[mstate].write(); assert(x);
+        const DataVecDeriv* b = bId[mstate].read(); assert(b);
+
+        doSolveLinearSystem(mparams, *x, *b);
     }
-    else msg_error() <<"Mass<DataTypes>::accFromF(const MechanicalParams* mparams, MultiVecDerivId aid) receives no mparam";
 }
 
-template<class DataTypes>
-void Mass<DataTypes>::accFromF(const MechanicalParams* /*mparams*/, DataVecDeriv& /*a*/, const DataVecDeriv& /*f*/)
+template <class DataTypes>
+void Mass<DataTypes>::doSolveLinearSystem(const MechanicalParams* mparams,
+    DataVecDeriv& x, const DataVecDeriv& b)
 {
-    msg_warning() << "Method accFromF(const MechanicalParams* , DataVecDeriv& , const DataVecDeriv& ) not implemented.";
-}
+    SOFA_UNUSED(mparams);
+    SOFA_UNUSED(x);
+    SOFA_UNUSED(b);
 
+    msg_warning() << "Method 'solveLinearSystem' was called but it is not implemented for '" <<
+        this->getClassName() << "'. Behavior is undefined. Try using a linear solver.";
+}
 
-template<class DataTypes>
+template <class DataTypes>
 void Mass<DataTypes>::addDForce(const MechanicalParams* mparams,
                                 DataVecDeriv & /*df*/, const DataVecDeriv & /*dx*/)
 {

diff --git a/Sofa/framework/Core/src/sofa/core/config.h.in b/Sofa/framework/Core/src/sofa/core/config.h.in
@@ -153,3 +153,10 @@ SOFA_ATTRIBUTE_DEPRECATED("v26.12", "v27.12", "Use BaseContext instead of Contex
 #define SOFA_CORE_DEPRECATED_RESETVEC() \
     SOFA_ATTRIBUTE_DEPRECATED("v26.12", "v27.12", "Use resetVec instead.")
 #endif
+
+#ifdef SOFA_BUILD_SOFA_CORE
+#define SOFA_CORE_DEPRECATED_ACCFROMF()
+#else
+#define SOFA_CORE_DEPRECATED_ACCFROMF() \
+SOFA_ATTRIBUTE_DISABLED("v26.12", "v27.06", "Use solveLinearSystem instead of accFromF.")
+#endif
diff --git a/Sofa/framework/Simulation/Core/CMakeLists.txt b/Sofa/framework/Simulation/Core/CMakeLists.txt
@@ -92,7 +92,6 @@ set(HEADER_FILES
     ${SRC_ROOT}/mappinggraph/VisitorApplication.h
     ${SRC_ROOT}/mappinggraph/MappingGraphUser.h
 
-    ${SRC_ROOT}/mechanicalvisitor/MechanicalAccFromFVisitor.h
     ${SRC_ROOT}/mechanicalvisitor/MechanicalAccumulateJacobian.h
     ${SRC_ROOT}/mechanicalvisitor/MechanicalAccumulateJacobian.h
     ${SRC_ROOT}/mechanicalvisitor/MechanicalAccumulateMatrixDeriv.h
@@ -118,6 +117,7 @@ set(HEADER_FILES
     ${SRC_ROOT}/mechanicalvisitor/MechanicalIdentityBlocksInJacobianVisitor.h
     ${SRC_ROOT}/mechanicalvisitor/MechanicalIntegrateConstraintVisitor.h
     ${SRC_ROOT}/mechanicalvisitor/MechanicalIntegrationVisitor.h
+    ${SRC_ROOT}/mechanicalvisitor/MechanicalMassLinearSolveVisitor.h
     ${SRC_ROOT}/mechanicalvisitor/MechanicalMultiVectorFromBaseVectorVisitor.h
     ${SRC_ROOT}/mechanicalvisitor/MechanicalMultiVectorPeqBaseVectorVisitor.h
     ${SRC_ROOT}/mechanicalvisitor/MechanicalMultiVectorToBaseVectorVisitor.h
@@ -246,7 +246,6 @@ set(SOURCE_FILES
     ${SRC_ROOT}/mappinggraph/MappingGraphVisitor.cpp
     ${SRC_ROOT}/mappinggraph/MappingGraphUser.cpp
 
-    ${SRC_ROOT}/mechanicalvisitor/MechanicalAccFromFVisitor.cpp
     ${SRC_ROOT}/mechanicalvisitor/MechanicalAccumulateJacobian.cpp
     ${SRC_ROOT}/mechanicalvisitor/MechanicalAccumulateJacobian.cpp
     ${SRC_ROOT}/mechanicalvisitor/MechanicalAccumulateMatrixDeriv.cpp
@@ -272,6 +271,7 @@ set(SOURCE_FILES
     ${SRC_ROOT}/mechanicalvisitor/MechanicalIdentityBlocksInJacobianVisitor.cpp
     ${SRC_ROOT}/mechanicalvisitor/MechanicalIntegrateConstraintVisitor.cpp
     ${SRC_ROOT}/mechanicalvisitor/MechanicalIntegrationVisitor.cpp
+    ${SRC_ROOT}/mechanicalvisitor/MechanicalMassLinearSolveVisitor.cpp
     ${SRC_ROOT}/mechanicalvisitor/MechanicalMultiVectorFromBaseVectorVisitor.cpp
     ${SRC_ROOT}/mechanicalvisitor/MechanicalMultiVectorPeqBaseVectorVisitor.cpp
     ${SRC_ROOT}/mechanicalvisitor/MechanicalMultiVectorToBaseVectorVisitor.cpp
@@ -345,6 +345,8 @@ set(DEPRECATED_HEADER_FILES
     ${DEPRECATED_DIR}/TaskSchedulerRegistry.h
     ${DEPRECATED_DIR}/UpdateMappingEndEvent.h
     ${DEPRECATED_DIR}/WorkerThread.h
+
+    ${DEPRECATED_DIR}/mechanicalvisitor/MechanicalAccFromFVisitor.h
 )
 
 sofa_find_package(Sofa.Core REQUIRED)

diff --git a/...work/Simulation/Core/compat/sofa/simulation/mechanicalvisitor/MechanicalAccFromFVisitor.h b/...work/Simulation/Core/compat/sofa/simulation/mechanicalvisitor/MechanicalAccFromFVisitor.h
@@ -0,0 +1,24 @@
+/******************************************************************************
+*                 SOFA, Simulation Open-Framework Architecture                *
+*                    (c) 2006 INRIA, USTL, UJF, CNRS, MGH                     *
+*                                                                             *
+* This program is free software; you can redistribute it and/or modify it     *
+* under the terms of the GNU Lesser General Public License as published by    *
+* the Free Software Foundation; either version 2.1 of the License, or (at     *
+* your option) any later version.                                             *
+*                                                                             *
+* This program is distributed in the hope that it will be useful, but WITHOUT *
+* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or       *
+* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License *
+* for more details.                                                           *
+*                                                                             *
+* You should have received a copy of the GNU Lesser General Public License    *
+* along with this program. If not, see <http://www.gnu.org/licenses/>.        *
+*******************************************************************************
+* Authors: The SOFA Team and external contributors (see Authors.txt)          *
+*                                                                             *
+* Contact information: contact@sofa-framework.org                             *
+******************************************************************************/
+#pragma once
+#include <sofa/simulation/mechanicalvisitor/MechanicalMassLinearSolveVisitor.h>
+SOFA_HEADER_DEPRECATED("v26.12", "v27.06", "sofa/simulation/mechanicalvisitor/MechanicalMassLinearSolveVisitor.h")