x (number or np.ndarray or Tensor or Pwc or Stf) – The object whose imaginary part you want to calculate, \(x\). For numbers,
arrays, and tensors, the object is converted to a tensor and then the operation is
applied. For functions of time (Pwcs and Stfs), the composition of the operation with
the function is computed (that is, the operation is applied to the function values).