Selective Determination of Floquet Quantities for the Efficient Assessment of Limit Cycle Stability and Oscillator Noise

We present a mixed time-frequency domain algorithm for the approximate computation of the Floquet quantities (exponents and both direct and adjoint eigenvectors) resulting from the linearization of index-1 differential-algebraic equations around a periodic limit cycle. The approach allows to select the number of Floquet exponents to be calculated approximating the matrix of the obtained eigenvalue problem. The error in the evaluation (for both exponents and eigenvectors) is proved to tend to zero along with the ratio between the norms of the neglected and retained rows of the relevant matrix.