class_docstr: Likes :class:`WelfordCovariance` but generalized to the arrowhead structure.
class_docstr_tok: ["Likes",":","class",":","`","WelfordCovariance","`","but","generalized","to","the","arrowhead","structure","."]
code: def reset(self):
      self._mean = 0.0
      self._m2_top = 0.0  # upper part, shape: head_size x matrix_size
      self._m2_bottom_diag = (
          0.0  # lower right part, shape: (matrix_size - head_size)
      )
      self.n_samples = 0
  
file_path: pyro/pyro/ops/welford.py
imports: import torch
label_desc: Use image node_id 2 for calling the WelfordArrowheadCovariance obj's underlying member method code with example usage: obj.reset() without return types