code: def apply_filter(E, wx):
      pols = E.shape[0]
      Ntaps = wx.shape[1]
      Xest = E.dtype.type(0)
      for k in range(pols):
          for i in range(Ntaps):
              Xest += E[k, i] * np.conj(wx[k, i])
      return Xest
  
imports: import numpy
label_desc: Use image node_id 4 for calling a global function with example usage: apply_filter(E, wx) and returns: Xest