code: def forward(self, x):
      p, a, b, c = self.p, self.a, self.b, self.c
      x_pow_p0 = x.pow(p - 1)
      x_pow_p1 = x_pow_p0 * x
      x_pow_p2 = x_pow_p1 * x
      return 1.0 / x + a * x_pow_p0 + b * x_pow_p1 + c * x_pow_p2
  
imports: import numpy
  import torch
  from scipy.optimize import brentq
  from scipy import special
  from math import pi
label_desc: Use image node_id 2 for calling the Envelope obj's underlying member method code with example usage: obj.forward(x) and returns: unknown