# EigSpectra¶

class acoular.spectra.EigSpectra

Provides the eigendecomposition of cross spectral matrix.

This class includes the efficient calculation of the full cross spectral matrix using the Welch method with windows and overlap and in addition its. eigenvalues and eigenvectors.

The result is computed only when needed, that is when the csm, eva or eve attribute is actually read. Any change in the input data or parameters leads to a new calculation, again triggered when csm is read. The result may be cached on disk in HDF5 files and need not to be recomputed during subsequent program runs with identical input data and parameters. The input data is taken to be identical if the source has identical parameters and the same file name in case of that the data is read from a file.

eva = Property( desc="eigenvalues of cross spectral matrix")

Eigenvalues of the cross spectral matrix as an (number of frequencies) array of floats, readonly.

eve = Property( desc="eigenvectors of cross spectral matrix")

Eigenvectors of the cross spectral matrix as an (number of frequencies, numchannels, numchannels) array of floats, readonly.

synthetic_ev(freq, num=0)

Return synthesized frequency band values of the eigenvalues.

Parameters:

freq : float

Band center frequency for which to return the results.

num : integer

Controls the width of the frequency bands considered; defaults to 3 (third-octave band).

num frequency band width
0 single frequency line
1 octave band
3 third-octave band
n 1/n-octave band
Returns:

float

Synthesized frequency band value of the eigenvalues (the sum of all values that are contained in the band).