Package org.ejml.interfaces.decomposition

Interface EigenDecomposition<T extends Matrix>

All Superinterfaces:
DecompositionInterface<T>
All Known Subinterfaces:
EigenDecomposition_F32<MatrixType>, EigenDecomposition_F64<MatrixType>
All Known Implementing Classes:
SwitchingEigenDecomposition_DDRM, SwitchingEigenDecomposition_FDRM, SymmetricQRAlgorithmDecomposition_DDRM, SymmetricQRAlgorithmDecomposition_FDRM, WatchedDoubleStepQRDecomposition_DDRM, WatchedDoubleStepQRDecomposition_FDRM
public interface EigenDecomposition<T extends Matrix> extends DecompositionInterface<T>

This is a generic interface for computing the eigenvalues and eigenvectors of a matrix. Eigenvalues and eigenvectors have the following property:

A*v=λ*v

where A is a square matrix and v is an eigenvector associated with the eigenvalue λ.

In general, both eigenvalues and eigenvectors can be complex numbers. For symmetric matrices the eigenvalues and eigenvectors are always real numbers. EJML does not support complex matrices but it does have minimal support for complex numbers. As a result complex eigenvalues are found, but only the real eigenvectors are computed.

To create a new instance of EigenDecomposition use DecompositionFactory_XXXX. If the matrix is known to be symmetric be sure to use the symmetric decomposition, which is much faster and more accurate than the general purpose one.

  • Method Details

    • getNumberOfEigenvalues

      int getNumberOfEigenvalues()
      Returns the number of eigenvalues/eigenvectors. This is the matrix's dimension.
      Returns:
      number of eigenvalues/eigenvectors.

    • getEigenVector

      T getEigenVector(int index)

      Used to retrieve real valued eigenvectors. If an eigenvector is associated with a complex eigenvalue then null is returned instead.

      Parameters:
      index - Index of the eigenvalue eigenvector pair.
      Returns:
      If the associated eigenvalue is real then an eigenvector is returned, null otherwise.