 Truncate method;
          = 'F':  use the balancing-free square-root
                  Balance & Truncate method;
          = 'S':  use the square-root Singular Perturbation
                  Approximation method;
          = 'P':  use the balancing-free square-root
                  Singular Perturbation Approximation method.

  EQUIL   CHARACTER*1
          Specifies whether the user wishes to preliminarily
          equilibrate the triplet (A,B,C) as follows:
          = 'S':  perform equilibration (sc