module fraktals
  implicit none
  contains

!-----------------------------------------------------
subroutine simple_julia(pic, cx, cy)
    implicit none
    integer, intent(inout), dimension (:,:)  ::  pic
    real, intent(in)                         ::  cx, cy

    integer      ::  ix, iy, width, height
    real         ::  fx, fy
    complex      ::  Z, C
    integer      ::  iter, maxiter

    width  = ubound(pic, 1)
    height = ubound(pic, 2)
    print *, "image size : ", width, height
    ! print *, "constante  : ", cx, cy

    maxiter = 500
    C = complex(cx, cy)
    print *, "C = ", C

    do ix = 1, width
      fx = (float(ix) / (float(width)/4.0) - 2.0)
      do iy = 1, height
        fy = (float(iy) / (float(height)/4.0) - 2.0)

          ! ------ traitement du pixel
          iter = 0
          Z = complex(fx, fy)
          do while ( (modulus2(Z) .LT. 4.0) .AND.     &
                     (iter < maxiter) )
            Z = (Z * Z) + C
            iter = iter + 1

          end do

          pic(ix, iy) = iter

          ! print *, ix, iy, "    ", fx, fy, "    ", iter

      enddo
    enddo 

end subroutine
!-----------------------------------------------------
function dist0 (x, y)
  implicit none
  real, intent(in)    :: x, y
  real                :: dist0
  dist0 = ( x*x + y*y )
end function

!-----------------------------------------------------
function modulus2(pt)
  implicit none
  complex, intent(in)    ::   pt
  real                   ::   modulus2
  modulus2 = real(pt)*real(pt) + imag(pt)*imag(pt)
end
!-----------------------------------------------------

end module fraktals