63 lines
1.9 KiB
Markdown
63 lines
1.9 KiB
Markdown
|
# EigenTridiagonalDC
|
|||
|
|
|
|||
|
|
Compute eigenvalues and eigenvectors of a symmetric tridiagonal matrix using the divide-and-conquer algorithm (LAPACK function [STEVD](https://www.intel.com/content/www/us/en/docs/onemkl/developer-reference-fortran/2025-2/stevd.html)).
|
|||
|
|
|
|||
|
|
Computing for type matrix<double>
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
bool matrix::EigenTridiagonalDC(
|
|||
|
|
ENUM_EIG_VALUES jobv, // compute eigenvectors or not
|
|||
|
|
vector& eigen_values, // vector of computed eigenvalues
|
|||
|
|
matrix& eigen_vectors // matrix of computed eigenvectors
|
|||
|
|
);
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
Computing for type matrix<float>
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
bool matrixf::EigenTridiagonalDC(
|
|||
|
|
ENUM_EIG_VALUES jobv, // compute eigenvectors or not
|
|||
|
|
vectorf& eigen_values, // vector of computed eigenvalues
|
|||
|
|
matrixf& eigen_vectors // matrix of computed eigenvectors
|
|||
|
|
);
|
|||
|
|
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
Parameters
|
|||
|
|
|
|||
|
|
jobv
|
|||
|
|
|
|||
|
|
[in] ENUM_EIG_VALUES enumeration value which determines the method for computing eigenvectors.
|
|||
|
|
|
|||
|
|
eigen_values
|
|||
|
|
|
|||
|
|
[out] Vector of eigenvalues.
|
|||
|
|
|
|||
|
|
eigen_vectors
|
|||
|
|
|
|||
|
|
[out] Matrix of eigenvectors.
|
|||
|
|
|
|||
|
|
Return Value
|
|||
|
|
|
|||
|
|
Return true if successful, otherwise false in case of an [error](/en/docs/constants/errorswarnings/errorcodes).
|
|||
|
|
|
|||
|
|
Note
|
|||
|
|
|
|||
|
|
Computation depends on the value of the jobv parameter.
|
|||
|
|
|
|||
|
|
When jobv = EIGVALUES_V, eigenvectors and eigenvalues are calculated.
|
|||
|
|
|
|||
|
|
If EIGVALUES_N is set, eigenvectors are not calculated. Only eigenvalues are computed.
|
|||
|
|
|
|||
|
|
The input must be a symmetric matrix in the tridiagonal form.
|
|||
|
|
|
|||
|
|
ENUM_EIG_VALUES
|
|||
|
|
|
|||
|
|
An enumeration that specifies whether to calculate eigenvectors.
|
|||
|
|
|
|||
|
|
| ID | Description |
|
|||
|
|
| --- | --- |
|
|||
|
|
| EIGVALUES_V | Eigenvectors and eigenvalues are calculated. |
|
|||
|
|
| EIGVALUES_N | Only eigenvalues are calculated, without vectors. |
|