def get_force_coefficients(*forces, coeff=1.0):
    """Convert forces to force coefficients.

    Parameters
    ----------
    forces : tuple of numpy.ndarray objects
        The forces.
    coeff : float (optional)
        The scaling coefficient; default: 1.0.

    Returns
    -------
    force_coeffs : tuple of numpy.ndarray objects
        The force coefficients.

    """
    force_coeffs = (coeff * f for f in forces)
    return force_coeffs