anchor.diff:    write(log,*) "TOTAL TIME: ", end-start
     close(log)
   
  +! Export plot to png
     call system('gnuplot -e ''set terminal png; set output "'//trim(filename)//'.png";'//&
       'set view map scale 1; set xrange [0:pi]; set yrange [0:pi];'//&
       'unset surface ; set pm3d; splot "'//trim(filename)//'"''')
  
positive.code:      -Uc,  0,   0,  V, &
         0, Uf,   V,  0 /)
  
    do i=1,100
      do j=1,10
        call write_data(i*0.5_dp,j*0.2_dp)
      end do
    end do
  
  
negative.code:   write(10, *) "Uf:    ", Uf
    close(10)
  
  do i=0,10
    V = i*0.01
  ! Set up matrix as an array of size 16
    Gkinv = (/ complex(dp) :: &
         0,  V, -Uc,  0, &
  