class_docstr: Tester distribution for default methods.
docstr: Quantile function = percent point function = inverse cdf.
docstr_tok: ["Quantile","function","=","percent","point","function","=","inverse","cdf","."]
code: def ppf(self, p):
      """Quantile function = percent point function = inverse cdf."""
      d = self.loc[p.index, p.columns]
      icdf_arr = d.mu + d.sigma * np.sqrt(2) * erfinv(2 * p.values - 1)
      return pd.DataFrame(icdf_arr, index=p.index, columns=p.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 2 for calling the _DistrDefaultMethodTester obj's underlying member method code with example usage: obj.ppf(p) and returns: pd