You can find Eigenvalues and Eigenvectors from mass and Stiffness matrix mm , kk from commamds 'Eigenvalues' or 'Eigenvectors' (both eigenvalues and eigenvectors ) with(LinearAlgebra): tmp:=LinearSolve(mm,kk,method='LU',inplace): (eig,eigvecs) := Eigenvectors(tmp); # both eig:=Eigenvalues(tmp) # only eigenvalues Vector 'eig' is also natural frequency of system and 'eigvecs' is mode vectors of system .