   //   result[i] = iteration(c[i]);
   // }
 
-  double lowerX = 0, upperX = 4;
+  double lowerX = -2, upperX = 2;
   double lowerY = -2, upperY = 2;
 
   int x, y;

  bitmap.pixels = new Pixel[bitmap.width * bitmap.height];
  cudaMemcpy(bitmap.pixels, devicePixels, sizeof(Pixel) * bitmap.width * bitmap.height, cudaMemcpyDeviceToHost);

  save_png_to_file(&bitmap, "fractal.png");

  cudaFree(devicePixels);
  cudaFree(devBitmap);

  double n;
  complex<double> z(0, 0);
  while ((n = norm(z)) < 4 && i < limit) {
    // z = z * z + c;
    // z = exp(z) - c;
    z = c * exp(-z) + z * z;
    ++i;
  }

