t feedback law.

  BETA    (input) DOUBLE PRECISION.
          The coefficient beta in the state feedback law.

  A       (input/output) DOUBLE PRECISION array, dimension (LDA,N)
          On entry, the leading N-by-N part of this array must
          contain the system state transition matrix A.
          On exit, the leading N-by-N part of this array contains
          the state matrix Ac of the closed-loop system.

  LDA     INTEGER
          The leading dimension of array A.  LDA &gt;= MAX(1,N).

  B   