*     ************************************************************************

      logical function gxnb(xstat)

*     ************************************************************************

*     Purpose :
*     ---------

*     This function checks if the status XSTAT corresponds to the
*     status of a nonbasic variable.

*     Parameters :
*     ------------

*     xstat   ( int )

*       input  : the status of the considered variable.
*       output : unmodified.

*     gxnb    ( log )

*       input  : meaningless.
*       output : .true.  iff the status XSTAT corresponds to
*                        the status of a nonbasic variable.
*                .false. otherwise.

*     Routines used :
*     ---------------

*     None.

*     Programming :
*     -------------

*     D. Tuyttens

*     ========================================================================

*     Routine parameter

      integer    xstat

      gxnb = mod(xstat,8).eq.2 .or. mod(xstat,8).eq.3

      return
      end