This DEMO application (Requires Internet Conecction) is a method of checking and teaching the Modal Spectrum Response Analysis in a detailed manner with precise results, breaking down the following:

-Mass Matrix
-Stiffness Matrix
-Eigenvalues (ω²)
-Angular Velocities (ω)
-Periods (T)
-Frequencies (f)
-Eigen vectors
-Normalization for each Mode Shape (phi ϕ)
-Proofs of orthogonality
-Participation factor
-Participation percentage for each Mode Shape

Mass and stiffness of each level must be entered, and so the spectral acceleration for each Mode Shape.