Calculation of Eigenvectors


I am trying to calculate the eigenvector of a tensor having components strain_xx, strain_xy, strain_yx and strain_yy using the python calculator. I have given the following expression, but did not work.
eigenvector([[strain_xx, strain_yx],[strain_xy, strain_yy]])

I am very new in Paraview. Can you please let me know how should I proceed?

Best regards