SOFA API  384d495c Open source framework for multi-physics simuation
sofa::component::odesolver::forward::EulerExplicitSolver Class Reference

`#include <EulerSolver.h>`

Inheritance diagram for sofa::component::odesolver::forward::EulerExplicitSolver:

## Detailed Description

The simplest time integration. Two variants of the Euler solver are available in this component:

• forward Euler method, also called explicit Euler method
• semi-implicit Euler method, also called semi-explicit Euler method or symplectic Euler

In both variants, acceleration is first computed. The system to compute the acceleration is M * a = f, where M is the mass matrix and f can be a force. In case of a diagonal mass matrix, M is trivially invertible and the acceleration can be computed without a linear solver.

f is accumulated by force fields through the addForce function. Mappings can also contribute by projecting forces of mapped objects. f is computed based on the current state (current velocity and position).

Explicit Euler method: The option "symplectic" must be set to false to use this variant. The explicit Euler method produces an approximate discrete solution by iterating x_{n+1} = x_n + v_n * dt v_{n+1} = v_n + a * dt

Semi-implicit Euler method: The option "symplectic" must be set to true to use this variant. The semi-implicit Euler method produces an approximate discrete solution by iterating v_{n+1} = v_n + a * dt x_{n+1} = x_n + v_{n+1} * dt

The semi-implicit Euler method is more robust than the standard Euler method.

## Public Attributes

Data< bool > d_symplectic
If true, the velocities are updated before the positions and the method is symplectic (more robust). If false, the positions are updated before the velocities (standard Euler, less robust). More...

If true, do not use realloc and free visitors in fwdInteractionForceField. More...

Public Attributes inherited from sofa::core::objectmodel::BaseObject
Data< bool > f_listening
if true, handle the events, otherwise ignore the events More...

Public Attributes inherited from sofa::core::objectmodel::Base
std::vector< lifecycle::DeprecatedData * > m_oldAttributes

Data< intd_messageLogCount

Data< std::string > name
Name of the object. More...

Data< bool > f_printLog
if true, emits extra messages at runtime. More...

Data< sofa::core::objectmodel::TagSetf_tags
list of the subsets the objet belongs to More...

Data< sofa::type::BoundingBoxf_bbox
this object bounding box More...

Data< sofa::core::objectmodel::ComponentStated_componentState
the object state More...

std::string m_definitionSourceFileName {""}

int m_definitionSourceFilePos {-1}

std::string m_instanciationSourceFileName {""}

int m_instanciationSourceFilePos {-1}

## Public Member Functions

SOFA_CLASS (EulerExplicitSolver, sofa::core::behavior::OdeSolver)

void solve (const core::ExecParams *params, SReal dt, sofa::core::MultiVecCoordId xResult, sofa::core::MultiVecDerivId vResult) override

SReal getIntegrationFactor (int inputDerivative, int outputDerivative) const override

SReal getSolutionIntegrationFactor (int outputDerivative) const override

void init () override
Initialization method called at graph creation and modification, during top-down traversal. More...

void parse (sofa::core::objectmodel::BaseObjectDescription *arg) override
Parse the given description to assign values to this object's fields and potentially other parameters. More...

Public Member Functions inherited from sofa::core::behavior::OdeSolver
SOFA_ABSTRACT_CLASS (OdeSolver, objectmodel::BaseObject)

virtual void solve (const core::ExecParams *params, SReal dt)

virtual void computeResidual (const core::ExecParams *, SReal, sofa::core::MultiVecCoordId, sofa::core::MultiVecDerivId)

virtual SReal getVelocityIntegrationFactor () const

virtual SReal getPositionIntegrationFactor () const

bool insertInNode (objectmodel::BaseNode *node) override

bool removeInNode (objectmodel::BaseNode *node) override

Public Member Functions inherited from sofa::core::objectmodel::BaseObject
SOFA_CLASS (BaseObject, Base)

virtual void draw (const core::visual::VisualParams *)
Render internal data of this object, for debugging purposes. More...

virtual void computeBBox (const core::ExecParams *, bool=false)

void setSrc (const std::string &v, std::vector< std::string > *attributeList=nullptr)
Sets a source Object and parses it to collect dependent Data. More...

void setSrc (const std::string &v, const BaseObject *loader, std::vector< std::string > *attributeList=nullptr)

virtual std::string getPathName () const override
Return the full path name of this object. More...

SReal getTime () const
Current time. More...

const BaseContextgetContext () const

BaseContextgetContext ()

const BaseObjectgetMaster () const

BaseObjectgetMaster ()

const VecSlavesgetSlaves () const

BaseObjectgetSlave (const std::string &name) const

virtual void removeSlave (BaseObject::SPtr s)

virtual void handleEvent (Event *)
Handle an event. More...

virtual void handleTopologyChange ()

virtual void handleTopologyChange (core::topology::Topology *t)

void parse (BaseObjectDescription *arg) override
Parse the given description to assign values to this object's fields and potentially other parameters. More...

virtual void bwdInit ()
Initialization method called at graph creation and modification, during bottom-up traversal. More...

virtual void reinit ()
Update method called when variables used in precomputation are modified. More...

void updateInternal ()
Update method called when variables (used to compute other internal variables) are modified. More...

virtual void storeResetState ()
Save the initial state for later uses in reset() More...

virtual void reset ()
Reset to initial state. More...

virtual void cleanup ()

Public Member Functions inherited from sofa::core::objectmodel::Base
virtual const BaseClassgetClass () const

void addUpdateCallback (const std::string &name, std::initializer_list< BaseData * > inputs, std::function< sofa::core::objectmodel::ComponentState(const DataTracker &)> function, std::initializer_list< BaseData * > outputs)

void addOutputsToCallback (const std::string &name, std::initializer_list< BaseData * > outputs)

const std::string & getName () const
Accessor to the object name. More...

void setName (const std::string &n)
Set the name of this object. More...

void setName (const std::string &n, int counter)
Set the name of this object, adding an integer counter. More...

std::string getTypeName () const
Get the type name of this object (i.e. class and template types) More...

virtual std::string getClassName () const
Get the class name of this object. More...

virtual std::string getTemplateName () const final
Get the template type names (if any) used to instantiate this object. More...

std::string getNameSpaceName () const
Get the template type names (if any) used to instantiate this object. More...

void setDefinitionSourceFileName (const std::string &sourceFileName)
Set the source filename (where the component is implemented) More...

const std::string & getDefinitionSourceFileName () const
Get the source filename (where the component is implemented) More...

void setDefinitionSourceFilePos (const int)
Set the source location (where the component is implemented) More...

int getDefinitionSourceFilePos () const
Get the source location (where the component is implemented) More...

void setInstanciationSourceFileName (const std::string &sourceFileName)

const std::string & getInstanciationSourceFileName () const

void setInstanciationSourceFilePos (const int)

int getInstanciationSourceFilePos () const

void addMessage (const sofa::helper::logging::Message &m) const

size_t countLoggedMessages (sofa::helper::logging::Message::TypeSet t=sofa::helper::logging::Message::AnyTypes) const

const std::deque< sofa::helper::logging::Message > & getLoggedMessages () const

const std::string getLoggedMessagesAsString (sofa::helper::logging::Message::TypeSet t=sofa::helper::logging::Message::AnyTypes) const

void clearLoggedMessages () const

bool notMuted () const

const sofa::core::objectmodel::TagSetgetTags () const
Represents the subsets the object belongs to. More...

bool hasTag (Tag t) const
Return true if the object belong to the given subset. More...

Add a subset qualification to the object. More...

void removeTag (Tag t)
Remove a subset qualification to the object. More...

ComponentState getComponentState () const

bool isComponentStateValid () const

virtual bool parseField (const std::string &attribute, const std::string &value)
Assign one field value (Data or Link) More...

virtual bool hasField (const std::string &attribute) const
Check if a given Data field or Link exists. More...

void parseFields (const std::list< std::string > &str)
Assign the field values stored in the given list of name + value pairs of strings. More...

virtual void parseFields (const std::map< std::string, std::string * > &str)
Assign the field values stored in the given map of name -> value pairs. More...

void writeDatas (std::map< std::string, std::string * > &str)
Write the current field values to the given map of name -> value pairs. More...

void writeDatas (std::ostream &out, const std::string &separator=" ")

BaseDatafindData (const std::string &name) const

std::vector< BaseData * > findGlobalField (const std::string &name) const
Find data fields given a name: several can be found as we look into the alias map. More...

Find link fields given a name: several can be found as we look into the alias map. More...

Update pointers in case the pointed-to objects have appeared. More...

template<class T >
BaseData::BaseInitData initData (::sofa::core::objectmodel::Data< T > *field, const char *name, const char *help, ::sofa::core::objectmodel::BaseData::DataFlags dataflags)
Helper method used to initialize a data field containing a value of type T. More...

template<class T >
BaseData::BaseInitData initData (Data< T > *field, const char *name, const char *help, bool isDisplayed=true, bool isReadOnly=false)
Helper method used to initialize a data field containing a value of type T. More...

template<class T >
Data< T >::InitData initData (Data< T > *field, const T &value, const char *name, const char *help, bool isDisplayed=true, bool isReadOnly=false)
Helper method used to initialize a data field containing a value of type T. More...

void addData (BaseData *f, const std::string &name)

void removeData (BaseData *f)
Remove a data field. More...

void addAlias (BaseData *field, const char *alias)
Add an alias to a Data. More...

const VecDatagetDataFields () const
Accessor to the vector containing all the fields of this object. More...

const MapDatagetDataAliases () const
Accessor to the map containing all the aliases of this object. More...

Accessor to the vector containing all the fields of this object. More...

Accessor to the map containing all the aliases of this object. More...

template<class T >

## Protected Member Functions

EulerExplicitSolver ()

void updateState (sofa::simulation::common::VectorOperations *vop, sofa::simulation::common::MechanicalOperations *mop, sofa::core::MultiVecCoordId xResult, sofa::core::MultiVecDerivId vResult, const sofa::core::behavior::MultiVecDeriv &acc, SReal dt) const

Protected Member Functions inherited from sofa::core::behavior::OdeSolver
OdeSolver ()

~OdeSolver () override

Protected Member Functions inherited from sofa::core::objectmodel::BaseObject
BaseObject ()

~BaseObject () override

virtual void doUpdateInternal ()
Implementation of the internal update. More...

void changeContextLink (BaseContext *before, BaseContext *&after)

This method insures that slaves objects have master and context links set correctly. More...

void trackInternalData (const BaseData &data)
Method called to add the Data to the DataTracker (listing the Data to track) More...

void cleanTracker ()

bool hasDataChanged (const BaseData &data)
Method called to know if a tracked Data has changed. More...

Protected Member Functions inherited from sofa::core::objectmodel::Base
Base ()

virtual ~Base ()

void initData0 (BaseData *field, BaseData::BaseInitData &res, const char *name, const char *help, bool isDisplayed=true, bool isReadOnly=false)
Helper method used by initData() More...

void initData0 (BaseData *field, BaseData::BaseInitData &res, const char *name, const char *help, BaseData::DataFlags dataFlags)
Helper method used by initData() More...

template<class T >
void initData0 (Data< T > *field, typename Data< T >::InitData &res, const T &value, const char *name, const char *help, bool isDisplayed=true, bool isReadOnly=false)
Helper method used by initData() More...

## Static Protected Member Functions

static void addSeparateGravity (sofa::simulation::common::MechanicalOperations *mop, SReal dt, core::MultiVecDerivId v)

static void computeForce (sofa::simulation::common::MechanicalOperations *mop, core::MultiVecDerivId f)
Assemble the force vector (right-hand side of the equation) More...

static void computeAcceleration (sofa::simulation::common::MechanicalOperations *mop, core::MultiVecDerivId acc, core::ConstMultiVecDerivId f)

static void projectResponse (sofa::simulation::common::MechanicalOperations *mop, core::MultiVecDerivId vecId)
Apply projective constraints, such as FixedConstraint. More...

static void solveConstraints (sofa::simulation::common::MechanicalOperations *mop, core::MultiVecDerivId acc)

static void assembleSystemMatrix (core::behavior::MultiMatrix< simulation::common::MechanicalOperations > *matrix)

static void solveSystem (core::behavior::MultiMatrix< simulation::common::MechanicalOperations > *matrix, core::MultiVecDerivId solution, core::MultiVecDerivId rhs)

Protected Attributes inherited from sofa::core::objectmodel::BaseObject

Protected Attributes inherited from sofa::core::objectmodel::Base
std::map< std::string, sofa::core::DataTrackerCallbackm_internalEngine

VecData m_vecData
List of fields (Data instances) More...

MapData m_aliasData
name -> Data multi-map (includes names and aliases) More...

name -> Link multi-map (includes names and aliases) More...

Static Public Member Functions inherited from sofa::core::objectmodel::BaseObject
template<class T >
static bool canCreate (T *, BaseContext *, BaseObjectDescription *)
Pre-construction check method called by ObjectFactory. More...

template<class T >
static T::SPtr create (T *, BaseContext *context, BaseObjectDescription *arg)
Construction method called by ObjectFactory. More...

Static Public Member Functions inherited from sofa::core::objectmodel::Base
static const BaseClassGetClass ()

template<class T >
static std::string shortName (const T *ptr=nullptr, BaseObjectDescription *=nullptr)

## ◆ d_symplectic

 Data sofa::component::odesolver::forward::EulerExplicitSolver::d_symplectic

If true, the velocities are updated before the positions and the method is symplectic (more robust). If false, the positions are updated before the velocities (standard Euler, less robust).

If true, do not use realloc and free visitors in fwdInteractionForceField.

## ◆ EulerExplicitSolver()

 sofa::component::odesolver::forward::EulerExplicitSolver::EulerExplicitSolver ( )
protected

## Function details

 void sofa::component::odesolver::forward::EulerExplicitSolver::addSeparateGravity ( sofa::simulation::common::MechanicalOperations * mop, SReal dt, core::MultiVecDerivId v )
staticprotected

Gravity times time step size is added to the velocity for some masses v += g * dt

## ◆ assembleSystemMatrix()

 void sofa::component::odesolver::forward::EulerExplicitSolver::assembleSystemMatrix ( core::behavior::MultiMatrix< simulation::common::MechanicalOperations > * matrix )
staticprotected

## ◆ computeAcceleration()

 void sofa::component::odesolver::forward::EulerExplicitSolver::computeAcceleration ( sofa::simulation::common::MechanicalOperations * mop, core::MultiVecDerivId acc, core::ConstMultiVecDerivId f )
staticprotected

Compute the acceleration from the force and the inverse of the mass acc = M^-1 * f

## ◆ computeForce()

 void sofa::component::odesolver::forward::EulerExplicitSolver::computeForce ( sofa::simulation::common::MechanicalOperations * mop, core::MultiVecDerivId f )
staticprotected

Assemble the force vector (right-hand side of the equation)

## ◆ getIntegrationFactor()

 SReal sofa::component::odesolver::forward::EulerExplicitSolver::getIntegrationFactor ( int inputDerivative, int outputDerivative ) const
overridevirtual

Given an input derivative order (0 for position, 1 for velocity, 2 for acceleration), how much will it affect the output derivative of the given order.

Reimplemented from sofa::core::behavior::OdeSolver.

## ◆ getSolutionIntegrationFactor()

 SReal sofa::component::odesolver::forward::EulerExplicitSolver::getSolutionIntegrationFactor ( int outputDerivative ) const
overridevirtual

Given a solution of the linear system, how much will it affect the output derivative of the given order.

Reimplemented from sofa::core::behavior::OdeSolver.

## ◆ init()

 void sofa::component::odesolver::forward::EulerExplicitSolver::init ( )
overridevirtual

Initialization method called at graph creation and modification, during top-down traversal.

Reimplemented from sofa::core::objectmodel::BaseObject.

## ◆ parse()

 void sofa::component::odesolver::forward::EulerExplicitSolver::parse ( sofa::core::objectmodel::BaseObjectDescription * arg )
overridevirtual

Parse the given description to assign values to this object's fields and potentially other parameters.

Reimplemented from sofa::core::objectmodel::Base.

## ◆ projectResponse()

 void sofa::component::odesolver::forward::EulerExplicitSolver::projectResponse ( sofa::simulation::common::MechanicalOperations * mop, core::MultiVecDerivId vecId )
staticprotected

Apply projective constraints, such as FixedConstraint.

## ◆ SOFA_CLASS()

 sofa::component::odesolver::forward::EulerExplicitSolver::SOFA_CLASS ( EulerExplicitSolver , sofa::core::behavior::OdeSolver )

## ◆ solve()

 void sofa::component::odesolver::forward::EulerExplicitSolver::solve ( const core::ExecParams * , SReal , sofa::core::MultiVecCoordId , sofa::core::MultiVecDerivId )
overridevirtual

Main computation method.

Specify and execute all computation for timestep integration, i.e. advancing the state from time t to t+dt, putting the resulting position and velocity in the provided vectors.

Implements sofa::core::behavior::OdeSolver.

## ◆ solveConstraints()

 void sofa::component::odesolver::forward::EulerExplicitSolver::solveConstraints ( sofa::simulation::common::MechanicalOperations * mop, core::MultiVecDerivId acc )
staticprotected

## ◆ solveSystem()

 void sofa::component::odesolver::forward::EulerExplicitSolver::solveSystem ( core::behavior::MultiMatrix< simulation::common::MechanicalOperations > * matrix, core::MultiVecDerivId solution, core::MultiVecDerivId rhs )
staticprotected