anchor.diff:            phi_i = atan2(y_i, x_i)
             dphi = abs(phi_i - geo%w3(p%icell%i3+1))
             if(dphi > pi) dphi = abs(dphi - twopi)
  -          if(dphi < 0.5 * pi) call insert_t(t2, 3, +1,e)
  -
  -       end if
  -
  -    end if
  -
  -    call find_next_wall(p%on_wall,tmin,id_min)
  +          if(dphi < 0.5 * pi) call insert_t(t2, 3, +1, 0._dp)
  +
  +       end if
  +
  +    end if
  +
  +    call find_next_wall(tnearest,id_min)
   
     end subroutine find_wall
   
  
positive.code:           phi_i = atan2(y_i, x_i)
            dphi = abs(phi_i - geo%w3(p%icell%i3))
            if(dphi > pi) dphi = abs(dphi - twopi)
            if(dphi < 0.5 * pi) call insert_t(t1, 3, -1,e)
  
         end if
         if(p%on_wall_id%w3 /= +1) then
  
negative.code:     call quadratic_pascal_reduced(pB,pC_2,t1,t2)
      if(p%on_wall_id%w1 == +1) then
         if(abs(t1) < abs(t2)) then
            call insert_t(t2, 1, +1, 3 * spacing(geo%w1(p%icell%i1 + 1)))
         else
            call insert_t(t1, 1, +1, 3 * spacing(geo%w1(p%icell%i1+1)))
         end if
      else
         call insert_t(t1,1, +1, 3 * spacing(geo%w1(p%icell%i1+1)))
         call insert_t(t2,1, +1, 3 * spacing(geo%w1(p%icell%i1+1)))
      end if
  
      ! -------------------------------------------------
  