OGS
ProcessLib::ForwardDifferencesJacobianAssembler Class Referencefinal

Detailed Description

Assembles the Jacobian matrix using forward differences.

Definition at line 17 of file ForwardDifferencesJacobianAssembler.h.

#include <ForwardDifferencesJacobianAssembler.h>

Inheritance diagram for ProcessLib::ForwardDifferencesJacobianAssembler:
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Collaboration diagram for ProcessLib::ForwardDifferencesJacobianAssembler:
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Public Member Functions

 ForwardDifferencesJacobianAssembler (std::vector< double > &&absolute_epsilons)
 
void assembleWithJacobian (LocalAssemblerInterface &local_assembler, double const t, double const dt, std::vector< double > const &local_x_data, std::vector< double > const &local_x_prev_data, std::vector< double > &local_b_data, std::vector< double > &local_Jac_data) override
 
std::unique_ptr< AbstractJacobianAssemblercopy () const override
 
- Public Member Functions inherited from ProcessLib::AbstractJacobianAssembler
virtual void assembleWithJacobianForStaggeredScheme (LocalAssemblerInterface &, double const, double const, Eigen::VectorXd const &, Eigen::VectorXd const &, int const, std::vector< double > &, std::vector< double > &)
 
virtual ~AbstractJacobianAssembler ()=default
 

Private Attributes

std::vector< double > const _absolute_epsilons
 
std::vector< double > _local_M_data
 
std::vector< double > _local_K_data
 
std::vector< double > _local_b_data
 
std::vector< double > _local_x_perturbed_data
 

Constructor & Destructor Documentation

◆ ForwardDifferencesJacobianAssembler()

ProcessLib::ForwardDifferencesJacobianAssembler::ForwardDifferencesJacobianAssembler ( std::vector< double > && absolute_epsilons)
explicit

Constructs a new instance.

Parameters
absolute_epsilonsperturbations of the components of the local solution vector used for evaluating the finite differences.
Note
The size of absolute_epsilons defines the "number of components" of the local solution vector (This is not the number of elements of the vector!). Therefore the size of the local solution vector must be divisible by the size of absolute_epsilons. This is the only consistency check performed. It is not checked whether said "number of components" is sensible. E.g., one could pass one epsilon per node, which would be valid but would not make sense at all.

Definition at line 18 of file ForwardDifferencesJacobianAssembler.cpp.

20 : _absolute_epsilons(std::move(absolute_epsilons))
21{
22 if (_absolute_epsilons.empty())
23 {
24 OGS_FATAL("No values for the absolute epsilons have been given.");
25 }
26}
#define OGS_FATAL(...)
Definition Error.h:26

References _absolute_epsilons, and OGS_FATAL.

Member Function Documentation

◆ assembleWithJacobian()

void ProcessLib::ForwardDifferencesJacobianAssembler::assembleWithJacobian ( LocalAssemblerInterface & local_assembler,
double const t,
double const dt,
std::vector< double > const & local_x_data,
std::vector< double > const & local_x_prev_data,
std::vector< double > & local_b_data,
std::vector< double > & local_Jac_data )
overridevirtual

Assembles the Jacobian, the matrices \(M\) and \(K\), and the vector \(b\). For the assembly the assemble() method of the given local_assembler is called several times and the Jacobian is built from finite differences. The number of calls of the assemble() method is \(2N+1\) if \(N\) is the size of local_x.

Attention
It is assumed that the local vectors and matrices are ordered by component.

Implements ProcessLib::AbstractJacobianAssembler.

Definition at line 28 of file ForwardDifferencesJacobianAssembler.cpp.

33{
34 std::vector<double> local_M_data(local_Jac_data.size());
35 std::vector<double> local_K_data(local_Jac_data.size());
36
37 // TODO do not check in every call.
38 if (local_x_data.size() % _absolute_epsilons.size() != 0)
39 {
41 "The number of specified epsilons ({:d}) and the number of local "
42 "d.o.f.s ({:d}) do not match, i.e., the latter is not divisible by "
43 "the former.",
44 _absolute_epsilons.size(), local_x_data.size());
45 }
46
47 auto const num_r_c =
48 static_cast<Eigen::MatrixXd::Index>(local_x_data.size());
49
50 auto const x = MathLib::toVector<Eigen::VectorXd>(local_x_data, num_r_c);
51 auto const x_prev =
52 MathLib::toVector<Eigen::VectorXd>(local_x_prev_data, num_r_c);
53
54 auto local_Jac =
55 MathLib::createZeroedMatrix(local_Jac_data, num_r_c, num_r_c);
56
57 auto const num_dofs_per_component =
58 local_x_data.size() / _absolute_epsilons.size();
59
60 // Assemble with unperturbed local x to get M0, K0, and b0 used in the
61 // finite differences below.
62 local_assembler.assemble(t, dt, local_x_data, local_x_prev_data,
63 local_M_data, local_K_data, local_b_data);
64
65 // Residual res := M xdot + K x - b
66 // Computing Jac := dres/dx
67 // = d(M xdot)/dx + d(K x)/dx - db/dx
68 for (Eigen::MatrixXd::Index i = 0; i < num_r_c; ++i)
69 {
70 // assume that local_x_data is ordered by component.
71 auto const component = i / num_dofs_per_component;
72 auto const eps = _absolute_epsilons[component];
73
74 // Assemble with perturbed local x.
75 _local_x_perturbed_data = local_x_data;
76 _local_x_perturbed_data[i] = local_x_data[i] + eps;
77 auto const x_p = MathLib::toVector<Eigen::VectorXd>(
79
80 local_assembler.assemble(t, dt, _local_x_perturbed_data,
81 local_x_prev_data, _local_M_data,
83
84 if (!local_M_data.empty() && !_local_M_data.empty())
85 {
86 auto const local_M_0 =
87 MathLib::toMatrix(local_M_data, num_r_c, num_r_c);
88 auto const local_M_p =
89 MathLib::toMatrix(_local_M_data, num_r_c, num_r_c);
90 local_Jac.col(i).noalias() +=
91 (local_M_p * (x_p - x_prev) - local_M_0 * (x - x_prev)) /
92 (dt * eps);
93 _local_M_data.clear();
94 }
95 if (!local_K_data.empty() && !_local_K_data.empty())
96 {
97 auto const local_K_0 =
98 MathLib::toMatrix(local_K_data, num_r_c, num_r_c);
99 auto const local_K_p =
100 MathLib::toMatrix(_local_K_data, num_r_c, num_r_c);
101 local_Jac.col(i).noalias() +=
102 (local_K_p * x_p - local_K_0 * x) / eps;
103 _local_K_data.clear();
104 }
105 if (!local_b_data.empty() && !_local_b_data.empty())
106 {
107 auto const local_b_0 =
108 MathLib::toVector<Eigen::VectorXd>(local_b_data, num_r_c);
109 auto const local_b_p =
110 MathLib::toVector<Eigen::VectorXd>(_local_b_data, num_r_c);
111 local_Jac.col(i).noalias() -= (local_b_p - local_b_0) / eps;
112 _local_b_data.clear();
113 }
114 }
115
116 local_M_data.clear();
117 local_K_data.clear();
118 local_b_data.clear();
119 // Assemble with unperturbed local x to keep the internal assembler state
120 // for next iteration or time step.
121 local_assembler.assemble(t, dt, local_x_data, local_x_prev_data,
122 local_M_data, local_K_data, local_b_data);
123
124 // Move the M and K contributions to the residuum for evaluation of nodal
125 // forces, flow rates, and the like. Cleaning up the M's and K's storage so
126 // it is not accounted for twice.
127 auto b = [&]()
128 {
129 if (!local_b_data.empty())
130 {
131 return MathLib::toVector<Eigen::VectorXd>(local_b_data, num_r_c);
132 }
133 return MathLib::createZeroedVector<Eigen::VectorXd>(local_b_data,
134 num_r_c);
135 }();
136
137 if (!local_M_data.empty())
138 {
139 auto M = MathLib::toMatrix(local_M_data, num_r_c, num_r_c);
140 b -= M * (x - x_prev) / dt;
141 local_M_data.clear();
142 }
143 if (!local_K_data.empty())
144 {
145 auto K = MathLib::toMatrix(local_K_data, num_r_c, num_r_c);
146 b -= K * x;
147 local_K_data.clear();
148 }
149}
Eigen::Map< Matrix > createZeroedMatrix(std::vector< double > &data, Eigen::MatrixXd::Index rows, Eigen::MatrixXd::Index cols)
Eigen::Map< const Matrix > toMatrix(std::vector< double > const &data, Eigen::MatrixXd::Index rows, Eigen::MatrixXd::Index cols)

References _absolute_epsilons, _local_b_data, _local_K_data, _local_M_data, _local_x_perturbed_data, ProcessLib::LocalAssemblerInterface::assemble(), MathLib::createZeroedMatrix(), OGS_FATAL, and MathLib::toMatrix().

◆ copy()

std::unique_ptr< AbstractJacobianAssembler > ProcessLib::ForwardDifferencesJacobianAssembler::copy ( ) const
overridevirtual

Implements ProcessLib::AbstractJacobianAssembler.

Definition at line 152 of file ForwardDifferencesJacobianAssembler.cpp.

153{
154 return std::make_unique<ForwardDifferencesJacobianAssembler>(*this);
155}

Member Data Documentation

◆ _absolute_epsilons

std::vector<double> const ProcessLib::ForwardDifferencesJacobianAssembler::_absolute_epsilons
private

◆ _local_b_data

std::vector<double> ProcessLib::ForwardDifferencesJacobianAssembler::_local_b_data
private

Definition at line 62 of file ForwardDifferencesJacobianAssembler.h.

Referenced by assembleWithJacobian().

◆ _local_K_data

std::vector<double> ProcessLib::ForwardDifferencesJacobianAssembler::_local_K_data
private

Definition at line 61 of file ForwardDifferencesJacobianAssembler.h.

Referenced by assembleWithJacobian().

◆ _local_M_data

std::vector<double> ProcessLib::ForwardDifferencesJacobianAssembler::_local_M_data
private

Definition at line 60 of file ForwardDifferencesJacobianAssembler.h.

Referenced by assembleWithJacobian().

◆ _local_x_perturbed_data

std::vector<double> ProcessLib::ForwardDifferencesJacobianAssembler::_local_x_perturbed_data
private

Definition at line 63 of file ForwardDifferencesJacobianAssembler.h.

Referenced by assembleWithJacobian().


The documentation for this class was generated from the following files: