Example:
  >>> x = torch.tensor([[0, 1, 2], [2, 1, 0]])
  >>> torch.corrcoef(x)
  tensor([[ 1., -1.],
          [-1.,  1.]])
  >>> x = torch.randn(2, 4)
  >>> x
  tensor([[-0.2678, -0.0908, -0.3766,  0.2780],
          [-0.5812,  0.1535,  0.2387,  0.2350]])
  >>> torch.corrcoef(x)
  tensor([[1.0000, 0.3582],
          [0.3582, 1.0000]])
  >>> torch.corrcoef(x[0])
  tensor(1.)
