code: def apply_old_coeffs(xy,coeffs):
      
      _theta = np.deg2rad(coeffs[1])
      _mrot = np.zeros(shape=(2,2),dtype=np.float64)
      _mrot[0] = (np.cos(_theta),np.sin(_theta))
      _mrot[1] = (-np.sin(_theta),np.cos(_theta))
  
      new_pos = (np.dot(xy,_mrot)/coeffs[2][0]) + coeffs[0]
  
      return new_pos
docs: Apply the offset/shift/rot values from a linear fit
          to an array of x,y positions.