chrono::modal::ChQuadraticEigenvalueSolverNullspaceDirect Class Reference

Description

Solves the eigenvalue problem with a direct method: first does LU factorization of Cq jacobians to find the null space, then solves the problem using the direct Eigen::EigenSolver.

Note: since intermediate dense matrices are built, the performance is acceptable only for small-sized problems. Note: since the method is direct, all eigenvalues are computed, regardless of n_modes, but only lower n_modes are returned.

#include <ChEigenvalueSolver.h>

Inheritance diagram for chrono::modal::ChQuadraticEigenvalueSolverNullspaceDirect:
Collaboration diagram for chrono::modal::ChQuadraticEigenvalueSolverNullspaceDirect:

Public Member Functions

virtual bool Solve (const ChSparseMatrix &M, const ChSparseMatrix &R, const ChSparseMatrix &K, const ChSparseMatrix &Cq, ChMatrixDynamic< std::complex< double >> &eigvects, ChVectorDynamic< std::complex< double >> &eigvals, ChVectorDynamic< double > &freq, ChVectorDynamic< double > &damping_ratio, ChEigenvalueSolverSettings settings=0) const override
 Solve the quadratic eigenvalue problem (lambda^2*M + lambda*R + K)*x = 0 s.t. More...
 
virtual bool Solve (ChAssembly &assembly, ChMatrixDynamic< std::complex< double >> &eigvects, ChVectorDynamic< std::complex< double >> &eigvals, ChVectorDynamic< double > &freq, ChVectorDynamic< double > &damping_ratio, ChEigenvalueSolverSettings settings=0) const override
 Solve the quadratic eigenvalue problem (lambda^2*M + lambda*R + K)*x = 0 s.t. More...
 
- Public Member Functions inherited from chrono::modal::ChQuadraticEigenvalueSolver
double GetTimeMatrixAssembly () const
 Get cumulative time for matrix assembly.
 
double GetTimeEigenSetup () const
 Get cumulative time eigensolver setup.
 
double GetTimeEigenSolver () const
 Get cumulative time eigensolver solution.
 
double GetTimeSolutionPostProcessing () const
 Get cumulative time for post-solver solution postprocessing.
 

Additional Inherited Members

- Protected Attributes inherited from chrono::modal::ChQuadraticEigenvalueSolver
ChTimer m_timer_matrix_assembly
 timer for matrix assembly
 
ChTimer m_timer_eigen_setup
 timer for eigensolver setup
 
ChTimer m_timer_eigen_solver
 timer for eigensolver solution
 
ChTimer m_timer_solution_postprocessing
 timer for conversion of eigensolver solution
 

Member Function Documentation

◆ Solve() [1/2]

virtual bool chrono::modal::ChQuadraticEigenvalueSolverNullspaceDirect::Solve ( ChAssembly assembly,
ChMatrixDynamic< std::complex< double >> &  eigvects,
ChVectorDynamic< std::complex< double >> &  eigvals,
ChVectorDynamic< double > &  freq,
ChVectorDynamic< double > &  damping_ratio,
ChEigenvalueSolverSettings  settings = 0 
) const
inlineoverridevirtual

Solve the quadratic eigenvalue problem (lambda^2*M + lambda*R + K)*x = 0 s.t.

Cq*x = 0 If n_modes=0, return all eigenvalues, otherwise only the first lower n_modes.

Parameters
assemblyassembly on which to apply the eigen solver
eigvectsoutput matrix with eigenvectors as columns, will be resized
eigvalsoutput vector with eigenvalues (real part not zero if some damping), will be resized
freqoutput vector with n undamped frequencies [Hz], as f=w/(2*PI), will be resized.
damping_ratiooutput vector with n damping rations r=damping/critical_damping.
settingsoptional: settings for the solver, or n. of desired lower eigenvalues. If =0, return all eigenvalues.

Implements chrono::modal::ChQuadraticEigenvalueSolver.

◆ Solve() [2/2]

bool chrono::modal::ChQuadraticEigenvalueSolverNullspaceDirect::Solve ( const ChSparseMatrix M,
const ChSparseMatrix R,
const ChSparseMatrix K,
const ChSparseMatrix Cq,
ChMatrixDynamic< std::complex< double >> &  eigvects,
ChVectorDynamic< std::complex< double >> &  eigvals,
ChVectorDynamic< double > &  freq,
ChVectorDynamic< double > &  damping_ratio,
ChEigenvalueSolverSettings  settings = 0 
) const
overridevirtual

Solve the quadratic eigenvalue problem (lambda^2*M + lambda*R + K)*x = 0 s.t.

Cq*x = 0 If n_modes=0, return all eigenvalues, otherwise only the first lower n_modes.

Parameters
Minput M matrix
Rinput R matrix
Kinput K matrix
Cqinput Cq matrix of constraint jacobians
eigvectsoutput matrix with eigenvectors as columns, will be resized
eigvalsoutput vector with complex eigenvalues (real part not zero if some damping), will be resized
freqoutput vector with n frequencies [Hz], as f=w/(2*PI), will be resized.
damping_ratiooutput vector with n damping rations r=damping/critical_damping.
settingsoptional: settings for the solver, or n. of desired lower eigenvalues. If =0, return all eigenvalues.

Implements chrono::modal::ChQuadraticEigenvalueSolver.


The documentation for this class was generated from the following files:
  • /builds/uwsbel/chrono/src/chrono_modal/ChEigenvalueSolver.h
  • /builds/uwsbel/chrono/src/chrono_modal/ChEigenvalueSolver.cpp