def set_passive_el(xmin, xval, passive_el):
    """ Sets the values of passive elements.

    Args:
        xmin (:obj:`numpy.array`): 
        xval (:obj:`numpy.array`): Indicates where there is mass.
        passive_el (:obj:`numpy.array`): Passive element nodes.

    Returns:
        A tuple with updated xmin and xval.
    """
    if xmin is not None:
        xmin[passive_el] = 0.99
    
    if xval is not None:
        xval[passive_el] = 1
    
    return xmin, xval