anchor.diff:             -Uc,  0,   0,  V, &
                0, Uf,   V,  0 /)
   
  -        call write_data(0.25_dp*j,0.1_dp)
  +        call write_data(0.0_dp,0.4_dp)
   !       end do
  -    end do
  +!     end do
     end do
   
     open(10, file="susy_qpi.log", position="append", status="old")
  
positive.code: ! Set constants
    Pi=4.0_dp*datan(1.0_dp)
  
    do i=0,4
      do j=0,4
  !       do k=0,4
  
  ! Set experimental data
  
negative.code:         mu  = 0.1_dp*t
          x0  = 0.02_dp
          epsf= 0.1_dp*x0
          Uc  = 0.1_dp*i
          Uf  = 0.1_dp*i
          V   = 0.1_dp
  
  ! Set up matrix as an array of size 16
  