verifyMean function

void verifyMean()

Implementation

void verifyMean() {
  final x = Tensor.fill([1, 4], 0.0);
  x.data = [1.0, 2.0, 3.0, 4.0];

  final loss = x.mean();
  loss.backward();

  final grads = x.grad;
  // d(mean(x))/dx should be 1/N. N=4, so [0.25, 0.25, 0.25, 0.25]
  bool ok = grads.every((g) => closeEnough(g, 0.25));
  print("MEAN: ${ok ? '✅ PASS' : '❌ FAIL (Expected 0.25, got $grads)'}");
}