generate mandelbrot set

mand.f95

program mand
  integer  , parameter :: width    =  1920*3
  integer  , parameter :: height    =  1080*3
  integer, dimension (width, height, 3) :: image
  integer :: col, row, iteration, max, max_rgb, pan_x
  real :: r_x, r_y, x, y, x_new, color_idx, zoom
  pan_x = -300
  pan_y = 0
  max = 1000
  max_rgb = 256**3
  zoom = 1
  do row = 0, height-1
     do col = 0, width-1
        c_re = ((pan_x+col)-width/2.0)*4.0/width
        c_im = ((pan_y+row) - height/2.0)*4.0/width
        c_re = c_re / zoom
        c_im = c_im / zoom
        x = 0.0
        y = 0.0
        iteration = 0
        do while(x*x+y*y <= 4.0 .and. iteration<max)
           x_new = x*x - y*y + c_re
           y = 2*x*y + c_im
           x = x_new
           iteration = iteration + 1
        end do
        if (iteration<max) then
           image(col+1, row+1, 1) = int(min(255, iteration*2))
           image(col+1, row+1, 2) = int(min(255, iteration*5))
           image(col+1, row+1, 3) = int(min(255, iteration*10))
        else
           image(col+1, row+1, 1) = 0
           image(col+1, row+1, 2) = 0
           image(col+1, row+1, 3) = 0
        end if
     end do
  end do
  open  (10, file = 'out.ppm')
  write (10, '(a/ i0, 1x, i0/ i0)') 'P3', width, height, 255
  do row = 0, height-1
     do col = 0, width-1
        write (10, '(i0)') image(col+1, row+1, 1), image(col+1, row+1, 2), image(col+1, row+1, 3)
     end do
  end do

  close(10)
end program mand