class_docstr: Tester distribution for default methods.
docstr: Probability density function.
docstr_tok: ["Probability","density","function","."]
code: def pdf(self, x):
      """Probability density function."""
      d = self.loc[x.index, x.columns]
      pdf_arr = np.exp(-0.5 * ((x.values - d.mu) / d.sigma) ** 2)
      pdf_arr = pdf_arr / (d.sigma * np.sqrt(2 * np.pi))
      return pd.DataFrame(pdf_arr, index=x.index, columns=x.columns)
  
file_path: sktime/sktime/proba/tests/test_base_default_methods.py
imports: import numpy
  import pandas
  from scipy.special import erfinv
  from sktime.proba.base import BaseDistribution
label_desc: Use image node_id 3 for calling the _DistrDefaultMethodTester obj's underlying member method code with example usage: obj.pdf(x) and returns: pd