ref="index.html#type-t">t</a> <span>&#45;&gt;</span> bool</code></dt><dt class="spec value" id="val-neg"><a href="#val-neg" class="anchor"></a><code><span class="keyword">val</span> neg : <a href="index.html#type-t">t</a> <span>&#45;&gt;</span> <a href="index.html#type-t">t</a></code></dt><dd><h2 id="interval-arithmetics-(forward-evaluation)"><a href="#interval-arithmetics-(forward-evaluation)" class="anchor"></a>INTERVAL ARITHMETICS (FORWARD EVALUATION)</h2></dd></dl><dl><dt class="spec value" id="val-abs"