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

      subroutine dcmach( epsmch, huge, tiny )

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

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

*     This routine computes the relative machine precision EPSMCH, a
*     very large number HUGE and a very small number TINY, depending 
*     on the machine that is used.  It also sets the constants ZERO 
*     and ONE to these values in double precision.

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

*     epsmch  ( dble )

*       input  : arbitrary.
*       output : the relative machine precision.

*     huge    ( dble )

*       input  : arbitrary.
*       output : the overflow limit of the machine.

*     tiny    ( dble )

*       input  : arbitrary.
*       output : the underflow limit of the machine.

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

*     dmach (blasd)

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

*     Ph.L. Toint 

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

*     Routine parameters

      double precision epsmch, huge, tiny

*     Internal variable

      integer          job

      double precision  zero, one, two, three, half, tenm1, tenm2, tenm4
      common / prbcst / zero, one, two, three, half, tenm1, tenm2, tenm4

*     Define the routine from blasd

      double precision dmach

*
*     Set 0.0 and 1.0
*
      zero   = 0.0d0
      one    = 1.0d0
      two    = 2.0d0
      three  = 3.0d0
      half   = 0.5d0
      tenm1  = 1.0d-1
      tenm2  = 1.0d-2
      tenm4  = 1.0d-4
*
*     Compute the machine epsilon
*
      job    = 1
      epsmch = dmach(job)
*
*     Compute the overflow limit
*
      job    = 3
      huge   = dmach(job)
*
*     Compute the underflow limit
*
      job    = 2
      tiny   = dmach(job)

      return
      end