code: def create_temporaries(self, r=True, f=True):
          
          inverse = isinstance(self, FourierTransformInverse)
  
          if inverse:
              rspace = self.range
              fspace = self.domain
          else:
              rspace = self.domain
              fspace = self.range
  
          if r:
              self._tmp_r = rspace.element().asarray()
          if f:
              self._tmp_f = fspace.element().asarray()
docs: Allocate and store reusable temporaries.
  
          Existing temporaries are overridden.
  
          Parameters
          ----------
          r : bool, optional
              Create temporary for the real space
          f : bool, optional
              Create temporary for the frequency space
  
          Notes
          -----
          To save memory, clear the temporaries when the transform is
          no longer used.
  
          See Also
          --------
          clear_temporaries
          clear_fftw_plan : can also hold references to the temporaries