2. Benchmark solution

The value of the estimate of the minimum of the Rayleigh quotient under inequality constraints (1.2), obtained from option DDL_STAB of the CRIT_STAB operator with the following parameters: NB_FREQ = 25 and COEF_DIM_ESPACE = 2, is \(3.430938E-8\) at the first time step for which the homogeneous solution is still stable and from \(-5.598244E-9\) at the second time step where the solution is theoretically unstable. These values are used as references and the test case is a case of non-regression.

We can see that with option DDL_STAB, we end up with an estimate of the stability criterion that is positive for the first time step, then negative for the second. The results are therefore in agreement with the theory, which validates the algorithm developed.