verifySum function

void verifySum()

Implementation

void verifySum() {
  final x = Tensor.fill([2, 2], 0.0);
  x.data = [1.0, 2.0, 3.0, 4.0];

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

  final grads = x.grad;
  // d(sum(x))/dx should be [1, 1, 1, 1]
  bool ok = grads.every((g) => closeEnough(g, 1.0));
  print("SUM: ${ok ? '✅ PASS' : '❌ FAIL (Expected grads of 1.0, got $grads)'}");
}