code: def test_ngd_step_no_groups(self):
      parameters = [
          torch.nn.Parameter(torch.tensor(2.5)),
          torch.nn.Parameter(torch.tensor([1.0, -0.5])),
      ]
      # parameters[0].grad = torch.tensor(1.)
      # parameters[1].grad = torch.tensor([2., -1.])
  
      optimizer = NGD(parameters, num_data=5, lr=0.1)
      optimizer.zero_grad()
      loss = parameters[0] + torch.dot(
          parameters[1], torch.tensor([2.0, -1])
      )
      loss.backward()
      optimizer.step()
  
      self.assertAllClose(parameters[0], torch.tensor(2.0))
      self.assertAllClose(parameters[1], torch.tensor([0.0, 0.0]))
  
file_path: gpytorch/test/optim/test_ngd.py
imports: import unittest
  import torch
  from gpytorch.optim import NGD
  from gpytorch.test.base_test_case import BaseTestCase
label_desc: Use image node_id 1 for calling the TestNGD obj's underlying member method code with example usage: obj.test_ngd_step_no_groups() without return types