</code> assume
    that all values of type <code>T</code> can be placed in a total order. If
    that is not true (<i>e.g.</i> Not-a-Number values in IEEE floating point
    arithmetic), then <code><a href=
    "#partially_ordered1">partially_ordered&lt;T&gt;</a></code> should be
    used. The <code><a href=
    "#partially_ordered1">partially_ordered&lt;T&gt;</a></code> template can
    be used for a totally-ordered type, but it is not as efficient as
    <code><a href=
    "#less_than_comparable1">less_th