Description
Class for computing eigenvalues/eigenvectors for the DAMPED constrained system.
It dispatches the settings to some solver of ChQuadraticEigenvalueSolver class. It handles multiple runs of the solver if one wants to find specific ranges of frequencies. Finally it guarantees that eigenvalues are sorted in the appropriate order of increasing eigenvalue modulus.
#include <ChEigenvalueSolver.h>
Public Member Functions | |
| ChModalSolveDamped (int n_lower_modes, double base_freq=1e-5, int max_iters=500, double mtolerance=1e-10, bool mverbose=false, const ChQuadraticEigenvalueSolver &asolver=ChQuadraticEigenvalueSolverNullspaceDirect()) | |
| Constructor for the case of N lower modes. More... | |
| ChModalSolveDamped (std::vector< ChFreqSpan > mfreq_spans, int max_iters=500, double mtolerance=1e-10, bool mverbose=false, const ChQuadraticEigenvalueSolver &asolver=ChQuadraticEigenvalueSolverNullspaceDirect()) | |
| Constructor for the case of multiple spans of frequency analysis ex. More... | |
| virtual int | 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 > &damp_ratios) const |
| Solve the constrained eigenvalue problem (-wsquare*M + K)*x = 0 s.t. More... | |
| virtual int | Solve (ChAssembly &assembly, ChMatrixDynamic< std::complex< double >> &eigvects, ChVectorDynamic< std::complex< double >> &eigvals, ChVectorDynamic< double > &freq, ChVectorDynamic< double > &damp_ratios) const |
| Solve the constrained eigenvalue problem (-wsquare*M + K)*x = 0 s.t. More... | |
Protected Attributes | |
| std::vector< ChFreqSpan > | freq_spans |
| double | tolerance = 1e-10 |
| tolerance for the iterative solver. | |
| int | max_iterations = 500 |
| upper limit for the number of iterations. If too low might not converge. | |
| bool | verbose = false |
| turn to true to see some diagnostic. | |
| const ChQuadraticEigenvalueSolver & | msolver |
Constructor & Destructor Documentation
◆ ChModalSolveDamped() [1/2]
|
inline |
Constructor for the case of N lower modes.
Ex. ChModalSolveDamped(7); finds first 7 lowest damped modes, using default settings (i.e. the ChQuadraticEigenvalueSolverNullspaceDirect solver). Ex. ChModalSolveDamped(5, 1e-5, 500, 1e-10, false, ChQuadraticEigenvalueSolverKrylovSchur()); finds first 5 lowest damped modes using the ChQuadraticEigenvalueSolverKrylovSchur() solver.
- Parameters
-
n_lower_modes n of lower modes base_freq frequency to whom the nodes are clustered. Use 1e-5 to get n lower modes. As sigma in shift&invert, as: sigma = -pow(base_freq * CH_2PI, 2). Too small gives ill conditioning (no convergence). Too large misses rigid body modes. max_iters upper limit for the number of iterations. If too low might not converge. mtolerance tolerance for the iterative solver. mverbose turn to true to see some diagnostic. asolver solver to use (default: direct, null-space based)
◆ ChModalSolveDamped() [2/2]
|
inline |
Constructor for the case of multiple spans of frequency analysis ex.
ChModalSolveDamped({{10,1e-5,},{5,40}} , 500); finds first 10 lower modes, then 5 modes closest to 40 Hz, etc., using multiple runs of the solver. Closest mean that some could be higher than 40Hz, others can be lower. Another example: suppose you want the 5 lowest modes, then you also are interested in 1 high frequency mode whose frequency is already know approximately, ex. 205 Hz, then you can do ChGeneralizedEigenvalueSolverGeneric({{5,1e-5,},{1,205}}, ...). Note about overlapping ranges: if n-th run finds frequencies up to X Hz, and the (n+1)-th run finds some frequency with Y Hz where Y < X, then such Y mode(s) is discarded.
- Parameters
-
mfreq_spans vector of {nmodes,freq}_i , will provide first nmodes_i starting at freq_i per each i vector entry max_iters upper limit for the number of iterations. If too low might not converge. mtolerance tolerance for the iterative solver. mverbose turn to true to see some diagnostic. asolver solver to use (default: direct, null-space based)
Member Function Documentation
◆ Solve() [1/2]
|
virtual |
Solve the constrained eigenvalue problem (-wsquare*M + K)*x = 0 s.t.
Cq*x = 0 Return the number of found modes, where n is not necessarily n_lower_modes (or the sum of ChFreqSpan::nmodes if multiple spans)
- Parameters
-
assembly input M matrix, n_v x n_v eigvects output matrix n x n_v with eigenvectors as columns, will be resized eigvals output vector with n eigenvalues, will be resized. freq output vector with n frequencies [Hz], as f=w/(2*PI), will be resized. damp_ratios output vector with n damping ratios, will be resized.
◆ Solve() [2/2]
|
virtual |
Solve the constrained eigenvalue problem (-wsquare*M + K)*x = 0 s.t.
Cq*x = 0 Return the n. of found modes, where n is not necessarily n_lower_modes (or the sum of ChFreqSpan::nmodes if multiple spans)
- Parameters
-
M input M matrix, n_v x n_v R input R matrix, n_v x n_v K input K matrix, n_v x n_v Cq input Cq matrix of constraint jacobians, n_c x n_v eigvects output matrix n x n_v with eigenvectors as columns, will be resized eigvals output vector with n eigenvalues, will be resized. freq output vector with n frequencies [Hz], as f=w/(2*PI), will be resized. damp_ratios output vector with n damping ratios, will be resized.
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
