I am trying to compute the eigenvalues of an NGSolve matrix originating from a bilinear form B. My attempt has been to follow the documentation and to create an numpy array using B.mat.NumPy() and B.NumPy(). However this gives me the error message

AttributeError: ‘ngsolve.la.SparseMatrixd’ object has no attribute ‘NumPy’

and

AttributeError: ‘ngsolve.comp.BilinearForm’ object has no attribute ‘NumPy’

respectively.

How can I create a numpy array using NGS-Py so that I work with the matrix using numpy?