anchor.diff:  c...  subroutine arguments
   c
         integer ierr
  -      integer ja(*),id(*),iwink(*),idx(*),iwinkx(*),idslp(*),ipslp(*)
  -      integer nfault(*),ien(*),lm(*),lmx(*),lmf(*),infiel(*),iddmat(*)
  -      integer ielno(*),iside(*),ihistry(*),mhist(*),infmat(*)
  -      integer infmatmod(*),infetype(*)
  +      integer ja(*)
  +      integer id(*),iwink(*)
  +      integer idx(*),iwinkx(*),idslp(*),ipslp(*)
  +      integer nfault(*)
  +      integer ien(*),lm(*),lmx(*),lmf(*),infiel(*),iddmat(*)
  +      integer ielno(*),iside(*),ihistry(*)
  +      integer mhist(*),infmat(*),infmatmod(*)
  +      integer infetype(*)
         character errstrng*(*)
  -      double precision alnz(*),pcg(*),zcg(*)
  -      double precision b(*),btot(*),bres(*),pvec(*),gvec1(*),gvec2(*)
  -      double precision grav(*)
  -      double precision x(*),d(*),deld(*),dprev(*),dcur(*),wink(*)
  +      double precision alnz(*),pcg(*),zcg(*),dprev(*)
  +      double precision bextern(*),btraction(*),bgravity(*),bconcforce(*)
  +      double precision bprestress(*),bintern(*),bresid(*),bwork(*)
  +      double precision dispvec(*),grav(*)
  +      double precision x(*),d(*),deld(*),dcur(*),wink(*)
         double precision dx(*),deldx(*),dxcur(*),winkx(*)
         double precision dfault(*),tfault(*)
         double precision s(*),stemp(*)
  
positive.code: c
          call fill(dcur,zero,ndof*numnp)
          call fill(dxcur,zero,ndof*numnp)
          call disp(gvec2,dcur,id,numnp,neq)
          if(numslp.ne.0) call disp(gvec2,dxcur,idx,numnp,neq)
  c
  c...rotate skewed coordinates to global system
  c
  
negative.code:      &     ierr,errstrng)                                               ! errcode
          else
            call stress_drv(
       &     bintern,neq,                                                 ! force
       &     x,d,numnp,                                                   ! global
       &     dx,numslp,                                                   ! slip
       &     tfault,numfn,                                                ! fault
  