e elementary reflectors used to compute the reduction.

  LDQ     INTEGER
          The leading dimension of the array Q.  LDQ &gt;= MAX(1,N).

  XA      (output) DOUBLE PRECISION array, dimension (LDXA,2*NB)
          On exit, the leading N-by-(2*NB) part of this array
          contains the matrix XA.

  LDXA    INTEGER
          The leading dimension of the array XA.  LDXA &gt;= MAX(1,N).

  XB      (output) DOUBLE PRECISION array, dimension (LDXB,2*NB)
          On exit, the leading (K+N)-by-(2*NB) part