class_docstr: Orthogonal (for weight=1) Fourier Polynomial on [0,pi]
  
  is orthogonal but first component does not square-integrate to 1
  final result seems to need a correction factor of sqrt(pi)
  _corfactor = sqrt(pi) from integrating the density
  
  Parameterization on [0, pi] from
  
  Peter Hall, Cross-Validation and the Smoothing of Orthogonal Series Density
  Estimators, JOURNAL OF MULTIVARIATE ANALYSIS 21, 189-206 (1987)
class_docstr_tok: ["Orthogonal","(","for","weight=1",")","Fourier","Polynomial","on","[","0",",","pi","]","is","orthogonal","but","first","component","does","not","square-integrate","to","1","final","result","seems","to","need","a","correction","factor","of","sqrt","(","pi",")","_corfactor","=","sqrt","(","pi",")","from","integrating","the","density","Parameterization","on","[","0",",","pi","]","from","Peter","Hall",",","Cross-Validation","and","the","Smoothing","of","Orthogonal","Series","Density","Estimators",",","JOURNAL","OF","MULTIVARIATE","ANALYSIS","21",",","189-206","(","1987",")"]
code: def __call__(self, x):
      if self.order == 0:
          return np.ones_like(x) / np.sqrt(np.pi)
      else:
          return sqr2 * np.cos(self.order * x) / np.sqrt(np.pi)
  
imports: from scipy import stats, integrate, special
  import numpy
label_desc: Use image node_id 2 for calling the F2Poly obj's underlying member method code with example usage: obj.__call__(x) and returns: unknown, unknown