Illegal value of 'lwork' in LAPACK.dtrsen

[henrikt-ma]

The dtrsen documentation makes it clear that lwork must not be zero:

    LWORK   (input) INTEGER
            The dimension of the array WORK.
            If JOB = 'N', LWORK >= max(1,N);
            if JOB = 'E', LWORK >= max(1,M*(N-M));
            if JOB = 'V' or 'B', LWORK >= max(1,2*M*(N-M)).

            If LWORK = -1, then a workspace query is assumed; the routine
            only calculates the optimal size of the WORK array, returns
            this value as the first entry of the WORK array, and no error
            message related to LWORK is issued by XERBLA.

Yet, this is what one gets for an empty matrix T unless job is "N":

  Integer lwork = if job == "N" then max(1, n) else if job == "E" then n * n else 2 * n * n;

This is triggered by the following call in ModelicaTest.Math.Matrices2:

  Real N[:, :] = fill(0, 0, 0);
  …
  Xn := Matrices.discreteRiccati(N, N, N, N);

In this case, the call to dtrsen comes via Modelica.Math.Matrices.Utilities.reorderRSF, where job is "E":

  (To, Qo, wr, wi) := LAPACK.dtrsen("E", "V", select, T, Q);