anchor.diff:  cdebug          write(6,*) "bconcforce:"
   cdebug          write(6,*) (bconcforce(idb),idb=1,200)
   cdebug        end if
  -cdebug        if(nprestrflag.ne.izero) then
  -cdebug          write(6,*) "bprestress:"
  -cdebug          write(6,*) (bprestress(idb),idb=1,200)
  -cdebug        end if
         else
           call fill(bresid,zero,neq)
         end if
  
positive.code: c~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  c
  c
        subroutine bsum(bextern,btraction,bgravity,bconcforce,bprestress,
       & bintern,bresid,nextflag,ntractflag,ngravflag,nconcflag,
       & nprestrflag,neq)
  c
  c...subroutine to sum all contributions to the external force vector,
  c   then subtract the internal force vector from the external vector
  
negative.code: c
  c...  subroutine arguments
  c
        integer nextflag,ntractflag,ngravflag,nconcflag,neq
        double precision bextern(nextflag*neq),btraction(ntractflag*neq)
        double precision bgravity(ngravflag*neq),bconcforce(nconcflag*neq)
        double precision bintern(neq),bresid(neq)
  c
  cdebug      integer idb
  c
  