anchor.diff:       DJac(3,2) = 0.0
        DJac(3,3) = -1.d0/ep - u
     else 
  -     DJac = 0.d0
  +     DJac(1,1) = 0.d0
  +     DJac(1,2) = 0.d0
  +     DJac(1,3) = 0.d0
  +
  +     DJac(2,1) = 0.d0
  +     DJac(2,2) = 0.d0
  +     DJac(2,3) = 0.d0
  +
  +     DJac(3,1) = 0.d0
  +     DJac(3,2) = 0.d0
        DJac(3,3) = -1.d0/ep
     end if
     ier = 0
  
positive.code:   y(1) = 3.9d0     ! u0
    y(2) = 1.1d0     ! v0
    y(3) = 2.8d0     ! w0
    rpar(1) = 1.2    ! a
    rpar(2) = 2.5    ! b
    rpar(3) = 1.d-5  ! ep
  
    ! set final solution
  
negative.code:   ytrue(3) = 2.4999733761419733
  
    ! set tolerances according to problem specifications
    atol = 1.d-9
    rtol = 1.d-6
    
    ! initialize vector module
  