def METHOD_NAME(reference_system, alchemical_system, positions, name="", platform=None):
    """Check that the forces of reference and modified systems are close.
    Parameters
    ----------
    reference_system : openmm.System
        Reference System
    alchemical_system : openmm.System
        System to compare to reference
    positions : openmm.unit.Quantity of shape [nparticles,3] with units of distance
        The particle positions to use
    name : str, optional, default=""
        System name to use for debugging.
    platform : openmm.Platform, optional, default=None
        If specified, use this platform
    """
    # Compute forces
    reference_force = compute_forces(reference_system, positions, platform=platform) / GLOBAL_FORCE_UNIT
    alchemical_force = compute_forces(alchemical_system, positions, platform=platform) / GLOBAL_FORCE_UNIT
    # Check that error is small.
    def magnitude(vec):
        return np.sqrt(np.mean(np.sum(vec**2, axis=1)))
    relative_error = magnitude(alchemical_force - reference_force) / magnitude(reference_force)
    if np.any(np.abs(relative_error) > MAX_FORCE_RELATIVE_ERROR):
        err_msg = ("Maximum allowable relative force error exceeded (was {:.8f}; allowed {:.8f}).\n"
                   "alchemical_force = {:.8f}, reference_force = {:.8f}, difference = {:.8f}")
        raise Exception(err_msg.format(relative_error, MAX_FORCE_RELATIVE_ERROR, magnitude(alchemical_force),
                                       magnitude(reference_force), magnitude(alchemical_force-reference_force)))