code: def reconstruct(self, b, X=None):
          
  
          if X is None:
              X = self.getcoef()
          Xf = sl.rfftn(X, None, self.cbpdn.cri.axisN)
          slc = (slice(None),)*self.dimN + \
                (slice(self.chncs[b], self.chncs[b+1]),)
          Sf = np.sum(self.cbpdn.Df[slc] * Xf, axis=self.cbpdn.cri.axisM)
          return sl.irfftn(Sf, self.cbpdn.cri.Nv, self.cbpdn.cri.axisN)
docs: Reconstruct representation of signal b in signal set.