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---
title: Math.sqrt()
slug: Web/JavaScript/Reference/Global_Objects/Math/sqrt
translation_of: Web/JavaScript/Reference/Global_Objects/Math/sqrt
---
<div>{{JSRef}}</div>
<p>La funzione <strong><code>Math.sqrt()</code></strong> ritorna la radice quadrata di un numero, cioè :</p>
<p><math display="block"><semantics><mrow><mo>∀</mo><mi>x</mi><mo>≥</mo><mn>0</mn><mo>,</mo><mstyle mathvariant="monospace"><mrow><mi>M</mi><mi>a</mi><mi>t</mi><mi>h</mi><mo>.</mo><mi>s</mi><mi>q</mi><mi>r</mi><mi>t</mi><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo></mrow></mstyle><mo>=</mo><msqrt><mi>x</mi></msqrt><mo>=</mo><mtext>the unique</mtext><mspace width="thickmathspace"></mspace><mi>y</mi><mo>≥</mo><mn>0</mn><mspace width="thickmathspace"></mspace><mtext>such that</mtext><mspace width="thickmathspace"></mspace><msup><mi>y</mi><mn>2</mn></msup><mo>=</mo><mi>x</mi></mrow><annotation encoding="TeX">\forall x \geq 0, \mathtt{Math.sqrt(x)} = \sqrt{x} = \text{l'unico} \; y \geq 0 \; \text{tale che} \; y^2 = x</annotation></semantics></math></p>
<h2 id="Sintassi">Sintassi</h2>
<pre class="syntaxbox"><code>Math.sqrt(<var>x</var>)</code></pre>
<h3 id="Parametri">Parametri</h3>
<dl>
<dt><code>x</code></dt>
<dd>Un numero.</dd>
</dl>
<h3 id="Valore_di_ritorno">Valore di ritorno</h3>
<p>La radice quadrata di un dato numero. Se il numero è negativo viene ritornato {{jsxref("NaN")}}.</p>
<h2 id="Descrizione">Descrizione</h2>
<p>Se il segno di <code>x</code> è negativo, <code>Math.sqrt()</code> ritorna {{jsxref("NaN")}}.</p>
<p>Siccome <code>sqrt()</code> è un metodo static di <code>Math</code>, puoi usarlo sempre come <code>Math.sqrt()</code>, piutttosto che come un metodo di un oggetto di tipo <code>Math</code> creato da te (<code>Math</code> non è un costruttore).</p>
<h2 id="Esempio">Esempio</h2>
<h3 id="Uso_di_Math.sqrt()">Uso di <code>Math.sqrt()</code></h3>
<pre class="brush: js">Math.sqrt(9); // 3
Math.sqrt(2); // 1.414213562373095
Math.sqrt(1); // 1
Math.sqrt(0); // 0
Math.sqrt(-1); // NaN
</pre>
<h2 id="Specificazioni">Specificazioni</h2>
<table class="standard-table">
<tbody>
<tr>
<th scope="col">Specification</th>
<th scope="col">Status</th>
<th scope="col">Comment</th>
</tr>
<tr>
<td>{{SpecName('ES1')}}</td>
<td>{{Spec2('ES1')}}</td>
<td>Definizione iniziale. Implementato per JavaScript 1.0.</td>
</tr>
<tr>
<td>{{SpecName('ES5.1', '#sec-15.8.2.17', 'Math.sqrt')}}</td>
<td>{{Spec2('ES5.1')}}</td>
<td> </td>
</tr>
<tr>
<td>{{SpecName('ES6', '#sec-math.sqrt', 'Math.sqrt')}}</td>
<td>{{Spec2('ES6')}}</td>
<td> </td>
</tr>
<tr>
<td>{{SpecName('ESDraft', '#sec-math.sqrt', 'Math.sqrt')}}</td>
<td>{{Spec2('ESDraft')}}</td>
<td> </td>
</tr>
</tbody>
</table>
<h2 id="Compatibilità_browser">Compatibilità browser</h2>
<div>{{CompatibilityTable}}</div>
<div id="compat-desktop">
<table class="compat-table">
<tbody>
<tr>
<th>Feature</th>
<th>Chrome</th>
<th>Firefox (Gecko)</th>
<th>Internet Explorer</th>
<th>Opera</th>
<th>Safari</th>
</tr>
<tr>
<td>Basic support</td>
<td>{{CompatVersionUnknown}}</td>
<td>{{CompatVersionUnknown}}</td>
<td>{{CompatVersionUnknown}}</td>
<td>{{CompatVersionUnknown}}</td>
<td>{{CompatVersionUnknown}}</td>
</tr>
</tbody>
</table>
</div>
<div id="compat-mobile">
<table class="compat-table">
<tbody>
<tr>
<th>Feature</th>
<th>Android</th>
<th>Chrome for Android</th>
<th>Firefox Mobile (Gecko)</th>
<th>IE Mobile</th>
<th>Opera Mobile</th>
<th>Safari Mobile</th>
</tr>
<tr>
<td>Basic support</td>
<td>{{CompatVersionUnknown}}</td>
<td>{{CompatVersionUnknown}}</td>
<td>{{CompatVersionUnknown}}</td>
<td>{{CompatVersionUnknown}}</td>
<td>{{CompatVersionUnknown}}</td>
<td>{{CompatVersionUnknown}}</td>
</tr>
</tbody>
</table>
</div>
<h2 id="Vedi_anche">Vedi anche</h2>
<ul>
<li>{{jsxref("Math.cbrt()")}}</li>
<li>{{jsxref("Math.exp()")}}</li>
<li>{{jsxref("Math.log()")}}</li>
<li>{{jsxref("Math.pow()")}}</li>
</ul>
|
