Reference documentation for deal.II version 9.5.0

#include <deal.II/lac/solver_gmres.h>
Classes  
struct  AdditionalData 
Public Types  
using  vector_type = VectorType 
Public Member Functions  
SolverGMRES (SolverControl &cn, VectorMemory< VectorType > &mem, const AdditionalData &data=AdditionalData())  
SolverGMRES (SolverControl &cn, const AdditionalData &data=AdditionalData())  
SolverGMRES (const SolverGMRES< VectorType > &)=delete  
template<typename MatrixType , typename PreconditionerType >  
void  solve (const MatrixType &A, VectorType &x, const VectorType &b, const PreconditionerType &preconditioner) 
boost::signals2::connection  connect_condition_number_slot (const std::function< void(double)> &slot, const bool every_iteration=false) 
boost::signals2::connection  connect_eigenvalues_slot (const std::function< void(const std::vector< std::complex< double > > &)> &slot, const bool every_iteration=false) 
boost::signals2::connection  connect_hessenberg_slot (const std::function< void(const FullMatrix< double > &)> &slot, const bool every_iteration=true) 
boost::signals2::connection  connect_krylov_space_slot (const std::function< void(const internal::SolverGMRESImplementation::TmpVectors< VectorType > &)> &slot) 
boost::signals2::connection  connect_re_orthogonalization_slot (const std::function< void(int)> &slot) 
boost::signals2::connection  connect (const std::function< SolverControl::State(const unsigned int iteration, const double check_value, const VectorType ¤t_iterate)> &slot) 
template<class Archive >  
void  serialize (Archive &ar, const unsigned int version) 
Subscriptor functionality  
Classes derived from Subscriptor provide a facility to subscribe to this object. This is mostly used by the SmartPointer class.  
void  subscribe (std::atomic< bool > *const validity, const std::string &identifier="") const 
void  unsubscribe (std::atomic< bool > *const validity, const std::string &identifier="") const 
unsigned int  n_subscriptions () const 
template<typename StreamType >  
void  list_subscribers (StreamType &stream) const 
void  list_subscribers () const 
Static Public Member Functions  
static ::ExceptionBase &  ExcTooFewTmpVectors (int arg1) 
static ::ExceptionBase &  ExcInUse (int arg1, std::string arg2, std::string arg3) 
static ::ExceptionBase &  ExcNoSubscriber (std::string arg1, std::string arg2) 
Protected Member Functions  
virtual double  criterion () 
void  givens_rotation (Vector< double > &h, Vector< double > &b, Vector< double > &ci, Vector< double > &si, int col) const 
Static Protected Member Functions  
static void  compute_eigs_and_cond (const FullMatrix< double > &H_orig, const unsigned int dim, const boost::signals2::signal< void(const std::vector< std::complex< double > > &)> &eigenvalues_signal, const boost::signals2::signal< void(const FullMatrix< double > &)> &hessenberg_signal, const boost::signals2::signal< void(double)> &cond_signal) 
Protected Attributes  
AdditionalData  additional_data 
boost::signals2::signal< void(double)>  condition_number_signal 
boost::signals2::signal< void(double)>  all_condition_numbers_signal 
boost::signals2::signal< void(const std::vector< std::complex< double > > &)>  eigenvalues_signal 
boost::signals2::signal< void(const std::vector< std::complex< double > > &)>  all_eigenvalues_signal 
boost::signals2::signal< void(const FullMatrix< double > &)>  hessenberg_signal 
boost::signals2::signal< void(const FullMatrix< double > &)>  all_hessenberg_signal 
boost::signals2::signal< void(const internal::SolverGMRESImplementation::TmpVectors< VectorType > &)>  krylov_space_signal 
boost::signals2::signal< void(int)>  re_orthogonalize_signal 
SolverControl &  solver_control 
FullMatrix< double >  H 
Vector< double >  gamma 
Vector< double >  ci 
Vector< double >  si 
Vector< double >  h 
GrowingVectorMemory< VectorType >  static_vector_memory 
VectorMemory< VectorType > &  memory 
boost::signals2::signal< SolverControl::State(const unsigned int iteration, const double check_value, const VectorType ¤t_iterate), StateCombiner >  iteration_status 
Private Types  
using  map_value_type = decltype(counter_map)::value_type 
using  map_iterator = decltype(counter_map)::iterator 
Private Member Functions  
void  check_no_subscribers () const noexcept 
Private Attributes  
std::atomic< unsigned int >  counter 
std::map< std::string, unsigned int >  counter_map 
std::vector< std::atomic< bool > * >  validity_pointers 
const std::type_info *  object_info 
Static Private Attributes  
static std::mutex  mutex 
Implementation of the Restarted Preconditioned Direct Generalized Minimal Residual Method. The stopping criterion is the norm of the residual.
The AdditionalData structure contains the number of temporary vectors used. The size of the Arnoldi basis is this number minus three. Additionally, it allows you to choose between right or left preconditioning. The default is left preconditioning. Finally it includes a flag indicating whether or not the default residual is used as stopping criterion.
AdditionalData
allows you to choose between left and right preconditioning. As expected, this switches between solving for the systems P^{1}A and AP^{1}, respectively.
A second consequence is the type of residual which is used to measure convergence. With left preconditioning, this is the preconditioned residual, while with right preconditioning, it is the residual of the unpreconditioned system.
Optionally, this behavior can be overridden by using the flag AdditionalData::use_default_residual. A true
value refers to the behavior described in the previous paragraph, while false
reverts it. Be aware though that additional residuals have to be computed in this case, impeding the overall performance of the solver.
The maximal basis size is controlled by AdditionalData::max_n_tmp_vectors, and it is this number minus 2. If the number of iteration steps exceeds this number, all basis vectors are discarded and the iteration starts anew from the approximation obtained so far.
Note that the minimizing property of GMRes only pertains to the Krylov space spanned by the Arnoldi basis. Therefore, restarted GMRes is not minimizing anymore. The choice of the basis length is a trade off between memory consumption and convergence speed, since a longer basis means minimization over a larger space.
For the requirements on matrices and vectors in order to work with this class, see the documentation of the Solver base class.
The solve() function of this class uses the mechanism described in the Solver base class to determine convergence. This mechanism can also be used to observe the progress of the iteration.
This class can estimate eigenvalues and condition number during the solution process. This is done by creating the Hessenberg matrix during the inner iterations. The eigenvalues are estimated as the eigenvalues of the Hessenberg matrix and the condition number is estimated as the ratio of the largest and smallest singular value of the Hessenberg matrix. The estimates can be obtained by connecting a function as a slot using connect_condition_number_slot
and connect_eigenvalues_slot
. These slots will then be called from the solver with the estimates as argument.
Definition at line 194 of file solver_gmres.h.

inherited 

privateinherited 
The data type used in counter_map.
Definition at line 230 of file subscriptor.h.

privateinherited 
The iterator type used in counter_map.
Definition at line 235 of file subscriptor.h.
SolverGMRES< VectorType >::SolverGMRES  (  SolverControl &  cn, 
VectorMemory< VectorType > &  mem,  
const AdditionalData &  data = AdditionalData() 

) 
Constructor.
SolverGMRES< VectorType >::SolverGMRES  (  SolverControl &  cn, 
const AdditionalData &  data = AdditionalData() 

) 
Constructor. Use an object of type GrowingVectorMemory as a default to allocate memory.

delete 
The copy constructor is deleted.
void SolverGMRES< VectorType >::solve  (  const MatrixType &  A, 
VectorType &  x,  
const VectorType &  b,  
const PreconditionerType &  preconditioner  
) 
Solve the linear system \(Ax=b\) for x.
boost::signals2::connection SolverGMRES< VectorType >::connect_condition_number_slot  (  const std::function< void(double)> &  slot, 
const bool  every_iteration = false 

) 
Connect a slot to retrieve the estimated condition number. Called on each outer iteration if every_iteration=true, otherwise called once when iterations are ended (i.e., either because convergence has been achieved, or because divergence has been detected).
boost::signals2::connection SolverGMRES< VectorType >::connect_eigenvalues_slot  (  const std::function< void(const std::vector< std::complex< double > > &)> &  slot, 
const bool  every_iteration = false 

) 
Connect a slot to retrieve the estimated eigenvalues. Called on each outer iteration if every_iteration=true, otherwise called once when iterations are ended (i.e., either because convergence has been achieved, or because divergence has been detected).
boost::signals2::connection SolverGMRES< VectorType >::connect_hessenberg_slot  (  const std::function< void(const FullMatrix< double > &)> &  slot, 
const bool  every_iteration = true 

) 
Connect a slot to retrieve the Hessenberg matrix obtained by the projection of the initial matrix on the Krylov basis. Called on each outer iteration if every_iteration=true, otherwise called once when iterations are ended (i.e., either because convergence has been achieved, or because divergence has been detected).
boost::signals2::connection SolverGMRES< VectorType >::connect_krylov_space_slot  (  const std::function< void(const internal::SolverGMRESImplementation::TmpVectors< VectorType > &)> &  slot  ) 
Connect a slot to retrieve the basis vectors of the Krylov space generated by the Arnoldi algorithm. Called at once when iterations are completed (i.e., either because convergence has been achieved, or because divergence has been detected).
boost::signals2::connection SolverGMRES< VectorType >::connect_re_orthogonalization_slot  (  const std::function< void(int)> &  slot  ) 
Connect a slot to retrieve a notification when the vectors are reorthogonalized.

protectedvirtual 
Implementation of the computation of the norm of the residual.

protected 
Transformation of an upper Hessenberg matrix into tridiagonal structure by givens rotation of the last column

staticprotected 
Estimates the eigenvalues from the Hessenberg matrix, H_orig, generated during the inner iterations. Uses these estimate to compute the condition number. Calls the signals eigenvalues_signal and cond_signal with these estimates as arguments.

inherited 
Connect a function object that will be called periodically within iterative solvers. This function is used to attach monitors to iterative solvers, either to determine when convergence has happened, or simply to observe the progress of an iteration. See the documentation of this class for more information.
slot  A function object specified here will, with each call, receive the number of the current iteration, the value that is used to check for convergence (typically the residual of the current iterate with respect to the linear system to be solved) and the currently best available guess for the current iterate. Note that some solvers do not update the approximate solution in every iteration but only after convergence or failure has been determined (GMRES is an example); in such cases, the vector passed as the last argument to the signal is simply the best approximate at the time the signal is called, but not the vector that will be returned if the signal's return value indicates that the iteration should be terminated. The function object must return a SolverControl::State value that indicates whether the iteration should continue, has failed, or has succeeded. The results of all connected functions will then be combined to determine what should happen with the iteration. 

inherited 
Subscribes a user of the object by storing the pointer validity
. The subscriber may be identified by text supplied as identifier
.
Definition at line 136 of file subscriptor.cc.

inherited 
Unsubscribes a user from the object.
identifier
and the validity
pointer must be the same as the one supplied to subscribe(). Definition at line 156 of file subscriptor.cc.

inlineinherited 
Return the present number of subscriptions to this object. This allows to use this class for reference counted lifetime determination where the last one to unsubscribe also deletes the object.
Definition at line 300 of file subscriptor.h.

inlineinherited 
List the subscribers to the input stream
.
Definition at line 317 of file subscriptor.h.

inherited 
List the subscribers to deallog
.
Definition at line 204 of file subscriptor.cc.

inlineinherited 
Read or write the data of this object to or from a stream for the purpose of serialization using the BOOST serialization library.
This function does not actually serialize any of the member variables of this class. The reason is that what this class stores is only who subscribes to this object, but who does so at the time of storing the contents of this object does not necessarily have anything to do with who subscribes to the object when it is restored. Consequently, we do not want to overwrite the subscribers at the time of restoring, and then there is no reason to write the subscribers out in the first place.
Definition at line 309 of file subscriptor.h.

privatenoexceptinherited 
Check that there are no objects subscribing to this object. If this check passes then it is safe to destroy the current object. It this check fails then this function will either abort or print an error message to deallog (by using the AssertNothrow mechanism), but will not throw an exception.
Definition at line 53 of file subscriptor.cc.

protected 
Includes the maximum number of tmp vectors.
Definition at line 355 of file solver_gmres.h.

protected 
Signal used to retrieve the estimated condition number. Called once when all iterations are ended.
Definition at line 361 of file solver_gmres.h.

protected 
Signal used to retrieve the estimated condition numbers. Called on each outer iteration.
Definition at line 367 of file solver_gmres.h.

protected 
Signal used to retrieve the estimated eigenvalues. Called once when all iterations are ended.
Definition at line 374 of file solver_gmres.h.

protected 
Signal used to retrieve the estimated eigenvalues. Called on each outer iteration.
Definition at line 381 of file solver_gmres.h.

protected 
Signal used to retrieve the Hessenberg matrix. Called once when all iterations are ended.
Definition at line 387 of file solver_gmres.h.

protected 
Signal used to retrieve the Hessenberg matrix. Called on each outer iteration.
Definition at line 394 of file solver_gmres.h.

protected 
Signal used to retrieve the Krylov space basis vectors. Called once when all iterations are ended.
Definition at line 402 of file solver_gmres.h.

protected 
Signal used to retrieve a notification when the vectors are reorthogonalized.
Definition at line 408 of file solver_gmres.h.

protected 
A reference to the underlying SolverControl object. In the regular case, this is not needed, as the signal from the base class is used, but the batched variant cannot use those mechanisms due to the high costs.
Definition at line 415 of file solver_gmres.h.

protected 
Projected system matrix
Definition at line 453 of file solver_gmres.h.

protected 
Auxiliary vector for orthogonalization
Definition at line 458 of file solver_gmres.h.

protected 
Auxiliary vector for orthogonalization
Definition at line 463 of file solver_gmres.h.

protected 
Auxiliary vector for orthogonalization
Definition at line 468 of file solver_gmres.h.

protected 
Auxiliary vector for orthogonalization
Definition at line 473 of file solver_gmres.h.

mutableprotectedinherited 

protectedinherited 

protectedinherited 
A signal that iterative solvers can execute at the end of every iteration (or in an otherwise periodic fashion) to find out whether we should continue iterating or not. The signal may call one or more slots that each will make this determination by themselves, and the result over all slots (function calls) will be determined by the StateCombiner object.
The arguments passed to the signal are (i) the number of the current iteration; (ii) the value that is used to determine convergence (oftentimes the residual, but in other cases other quantities may be used as long as they converge to zero as the iterate approaches the solution of the linear system); and (iii) a vector that corresponds to the current best guess for the solution at the point where the signal is called. Note that some solvers do not update the approximate solution in every iteration but only after convergence or failure has been determined (GMRES is an example); in such cases, the vector passed as the last argument to the signal is simply the best approximate at the time the signal is called, but not the vector that will be returned if the signal's return value indicates that the iteration should be terminated.

mutableprivateinherited 
Store the number of objects which subscribed to this object. Initially, this number is zero, and upon destruction it shall be zero again (i.e. all objects which subscribed should have unsubscribed again).
The creator (and owner) of an object is counted in the map below if HE manages to supply identification.
We use the mutable
keyword in order to allow subscription to constant objects also.
This counter may be read from and written to concurrently in multithreaded code: hence we use the std::atomic
class template.
Definition at line 219 of file subscriptor.h.

mutableprivateinherited 
In this map, we count subscriptions for each different identification string supplied to subscribe().
Definition at line 225 of file subscriptor.h.

mutableprivateinherited 
In this vector, we store pointers to the validity bool in the SmartPointer objects that subscribe to this class.
Definition at line 241 of file subscriptor.h.

mutableprivateinherited 
Pointer to the typeinfo object of this object, from which we can later deduce the class name. Since this information on the derived class is neither available in the destructor, nor in the constructor, we obtain it in between and store it here.
Definition at line 249 of file subscriptor.h.

staticprivateinherited 
A mutex used to ensure data consistency when printing out the list of subscribers.
Definition at line 271 of file subscriptor.h.