A &gt;= MAX(1,M).

  B       (input/output) DOUBLE PRECISION array, dimension (LDB,N)
          On entry, the leading M-by-N part of this array must
          contain the matrix B.
          On exit, the leading M-by-N part of this array contains
          the matrix [ R21  R22 ] and, in the zero parts of B,
          information about the elementary reflectors used to
          compute the symplectic QR decomposition.

  LDB     INTEGER
          The leading dimension of the array B.  LDB &gt;= MAX(1,M).

