def apply_old_coeffs(xy,coeffs):
    """ Apply the offset/shift/rot values from a linear fit
        to an array of x,y positions.
    """
    _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
Apply the offset/shift/rot values from a linear fit
        to an array of x,y positions.