NumericAnnex/docsets/NumericAnnex.docset/Contents/Resources/Documents/Classes/Random.html

357 lines
18 KiB
HTML
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Random Class Reference</title>
<link rel="stylesheet" type="text/css" href="../css/highlight.css">
<link rel="stylesheet" type="text/css" href="../css/jazzy.css">
<script src="../js/jquery.min.js" defer></script>
<script src="../js/jazzy.js" defer></script>
</head>
<body>
<a name="//apple_ref/swift/Class/Random" class="dashAnchor"></a>
<a title="Random Class Reference"></a>
<header>
<p class="primary">
<a href="../index.html">NumericAnnex Reference</a>
(100% documented)
</p>
<p>
<a href="https://github.com/xwu/NumericAnnex">View on GitHub</a>
</p>
<p>
<a href="dash-feed://https%3A%2F%2Fxwu%2Egithub%2Eio%2FNumericAnnex%2Fdocsets%2FNumericAnnex%2Exml">Install in Dash</a>
</p>
</header>
<div class="wrapper">
<nav>
<ul>
<li>
<p><a href="../Classes.html">Classes</a></p>
<ul>
<li>
<a href="../Classes/Random.html">Random</a>
</li>
<li>
<a href="../Classes/Random/Xoroshiro.html"> Xoroshiro</a>
</li>
</ul>
</li>
<li>
<p><a href="../Extensions.html">Extensions</a></p>
<ul>
<li>
<a href="../Extensions/BinaryInteger.html">BinaryInteger</a>
</li>
<li>
<a href="../Extensions/Double.html">Double</a>
</li>
<li>
<a href="../Extensions/Float.html">Float</a>
</li>
<li>
<a href="../Extensions/FloatingPoint.html">FloatingPoint</a>
</li>
<li>
<a href="../Extensions/UnsignedInteger.html">UnsignedInteger</a>
</li>
</ul>
</li>
<li>
<p><a href="../Functions.html">Functions</a></p>
<ul>
<li>
<a href="../Functions.html#/s:12NumericAnnex3absAA7ComplexVyxGAeA4RealRzs9DecodableRzs9EncodableRzs33_ExpressibleByBuiltinFloatLiteralRzlF">abs(_:)</a>
</li>
<li>
<a href="../Functions.html#/s:12NumericAnnex3absAA8RationalVyxGAEs9DecodableRzs9EncodableRzs13SignedIntegerRzs021_ExpressibleByBuiltinH7LiteralRzs08UnsignedH09Magnitudes0A0PRpzAkM_AKQZANRSlF">abs(_:)</a>
</li>
<li>
<a href="../Functions.html#/s:12NumericAnnex4ceilAA8RationalVyxGAEs9DecodableRzs9EncodableRzs13SignedIntegerRzs021_ExpressibleByBuiltinH7LiteralRzs08UnsignedH09Magnitudes0A0PRpzAkM_AKQZANRSlF">ceil(_:)</a>
</li>
<li>
<a href="../Functions.html#/s:12NumericAnnex5floorAA8RationalVyxGAEs9DecodableRzs9EncodableRzs13SignedIntegerRzs021_ExpressibleByBuiltinH7LiteralRzs08UnsignedH09Magnitudes0A0PRpzAkM_AKQZANRSlF">floor(_:)</a>
</li>
<li>
<a href="../Functions.html#/s:12NumericAnnex5roundAA8RationalVyxGAEs9DecodableRzs9EncodableRzs13SignedIntegerRzs021_ExpressibleByBuiltinH7LiteralRzs08UnsignedH09Magnitudes0A0PRpzAkM_AKQZANRSlF">round(_:)</a>
</li>
<li>
<a href="../Functions.html#/s:12NumericAnnex4sqrtAA7ComplexVyxGAeA4RealRzs9DecodableRzs9EncodableRzs33_ExpressibleByBuiltinFloatLiteralRzlF">sqrt(_:)</a>
</li>
<li>
<a href="../Functions.html#/s:12NumericAnnex5truncAA8RationalVyxGAEs9DecodableRzs9EncodableRzs13SignedIntegerRzs021_ExpressibleByBuiltinH7LiteralRzs08UnsignedH09Magnitudes0A0PRpzAkM_AKQZANRSlF">trunc(_:)</a>
</li>
</ul>
</li>
<li>
<p><a href="../Protocols.html">Protocols</a></p>
<ul>
<li>
<a href="../Protocols/Math.html">Math</a>
</li>
<li>
<a href="../Protocols/PRNG.html">PRNG</a>
</li>
<li>
<a href="../Protocols/Real.html">Real</a>
</li>
</ul>
</li>
<li>
<p><a href="../Structs.html">Structs</a></p>
<ul>
<li>
<a href="../Structs/Complex.html">Complex</a>
</li>
<li>
<a href="../Structs/Rational.html">Rational</a>
</li>
</ul>
</li>
<li>
<p><a href="../Typealiases.html">Typealiases</a></p>
<ul>
<li>
<a href="../Typealiases.html#/s:12NumericAnnex12RoundingRulea">RoundingRule</a>
</li>
<li>
<a href="../Typealiases.html#/s:12NumericAnnex4Signa">Sign</a>
</li>
</ul>
</li>
</ul>
</nav>
<article>
<section>
<div class="wrapper">
<div class="overview">
<h1>Random</h1>
<div class="declaration">
<div class="language">
<pre class="highlight"><code><span class="kd">public</span> <span class="kd">final</span> <span class="kd">class</span> <span class="kt">Random</span> <span class="p">:</span> <span class="kt"><a href="../Protocols/PRNG.html">PRNG</a></span></code></pre>
</div>
</div>
<p>A pseudo-random number generator (PRNG) that implements
<a href="http://vigna.di.unimi.it/ftp/papers/xorshiftplus.pdf"><code>xorshift128+</code></a>, an efficient linear-feedback shift register.</p>
<div class="aside aside-warning">
<p class="aside-title">Warning</p>
Once seeded from cryptographically secure random bytes, an
instance of <code>Random</code> generates high-quality random numbers but is <em>not</em> a
cryptographically secure PRNG.
</div>
<p>To generate random numbers, create your own instance of <code>Random</code> with an
internal state seeded from cryptographically secure random bytes:</p>
<pre class="highlight swift"><code><span class="k">let</span> <span class="nv">random</span> <span class="o">=</span> <span class="kt">Random</span><span class="p">()</span><span class="o">!</span>
<span class="k">let</span> <span class="nv">x</span> <span class="o">=</span> <span class="n">random</span><span class="o">.</span><span class="nf">uniform</span><span class="p">()</span> <span class="k">as</span> <span class="kt">Int</span>
<span class="c1">// You can also pass the desired result type as an argument.</span>
<span class="k">let</span> <span class="nv">y</span> <span class="o">=</span> <span class="n">random</span><span class="o">.</span><span class="nf">uniform</span><span class="p">(</span><span class="kt">Int</span><span class="o">.</span><span class="k">self</span><span class="p">)</span>
<span class="k">if</span> <span class="n">x</span> <span class="o">&gt;</span> <span class="n">y</span> <span class="p">{</span>
<span class="nf">print</span><span class="p">(</span><span class="s">"Here's a random value between 0 and 42 (inclusive):"</span><span class="p">)</span>
<span class="nf">print</span><span class="p">(</span><span class="n">random</span><span class="o">.</span><span class="nf">uniform</span><span class="p">(</span><span class="nv">a</span><span class="p">:</span> <span class="mi">0</span><span class="p">,</span> <span class="nv">b</span><span class="p">:</span> <span class="mi">42</span><span class="p">))</span>
<span class="p">}</span> <span class="k">else</span> <span class="p">{</span>
<span class="nf">print</span><span class="p">(</span><span class="s">"Here's a random value between -42 and 0 (inclusive):"</span><span class="p">)</span>
<span class="nf">print</span><span class="p">(</span><span class="n">random</span><span class="o">.</span><span class="nf">uniform</span><span class="p">(</span><span class="nv">a</span><span class="p">:</span> <span class="o">-</span><span class="mi">42</span><span class="p">,</span> <span class="nv">b</span><span class="p">:</span> <span class="mi">0</span><span class="p">))</span>
<span class="p">}</span>
</code></pre>
<div class="aside aside-see-also">
<p class="aside-title">See also</p>
<code><a href="../Classes/Random/Xoroshiro.html">Random.Xoroshiro</a></code>, <code><a href="../Protocols/PRNG.html">PRNG</a></code>
</div>
</div>
</div>
</section>
<section class="toc">
<details open>
<summary>Topics</summary>
<div class="wrapper">
<ul>
<li><a href="#/s:12NumericAnnex6RandomC5states6UInt64V_AFtv">state</a></li>
<li><a href="#/s:12NumericAnnex6RandomCACs6UInt64V_AEt5state_tcfc">init(state:)</a></li>
<li><a href="#/s:12NumericAnnex6RandomCACSgycfc">init()</a></li>
<li><a href="#/s:s16IteratorProtocolP4next7ElementQzSgyF">next()</a></li>
</ul>
<ul>
<li><a href="#/s:12NumericAnnex6RandomC9XoroshiroC">Xoroshiro</a></li>
</ul>
</div>
</details>
</section>
<section>
<div class="wrapper">
<div class="group">
<ul>
<li>
<div>
<a name="/s:12NumericAnnex6RandomC5states6UInt64V_AFtv"></a>
<a name="//apple_ref/swift/Property/state" class="dashAnchor"></a>
<h4>
<code>state</code>
</h4>
</div>
<div class="abstract">
<p>The internal state of the pseudo-random number generator.</p>
</div>
<div class="declaration">
<h5>Declaration</h5>
<div class="language">
<p class="aside-title">Swift</p>
<pre class="highlight"><code><span class="kd">public</span> <span class="k">var</span> <span class="nv">state</span><span class="p">:</span> <span class="p">(</span><span class="kt">UInt64</span><span class="p">,</span> <span class="kt">UInt64</span><span class="p">)</span></code></pre>
</div>
</div>
</li>
<li>
<div>
<a name="/s:12NumericAnnex6RandomCACs6UInt64V_AEt5state_tcfc"></a>
<a name="//apple_ref/swift/Method/init(state:)" class="dashAnchor"></a>
<h4>
<code>init(state:)</code>
</h4>
</div>
<div class="abstract">
<p>Creates a pseudo-random number generator with the given internal state.</p>
</div>
<div class="declaration">
<h5>Declaration</h5>
<div class="language">
<p class="aside-title">Swift</p>
<pre class="highlight"><code><span class="kd">public</span> <span class="nf">init</span><span class="p">(</span><span class="nv">state</span><span class="p">:</span> <span class="p">(</span><span class="kt">UInt64</span><span class="p">,</span> <span class="kt">UInt64</span><span class="p">))</span></code></pre>
</div>
</div>
<div class="parameters">
<h5>Parameters</h5>
<dl>
<dt><code>state</code></dt>
<dd>
<p>The value to be used as the generator&rsquo;s internal state.</p>
</dd>
</dl>
</div>
</li>
<li>
<div>
<a name="/s:12NumericAnnex6RandomCACSgycfc"></a>
<a name="//apple_ref/swift/Method/init()" class="dashAnchor"></a>
<h4>
<code>init()</code>
</h4>
</div>
<div class="abstract">
<p>Creates a pseudo-random number generator with an internal state seeded
using cryptographically secure random bytes.</p>
<p>If cryptographically secure random bytes are unavailable, the result is
<code>nil</code>.</p>
</div>
<div class="declaration">
<h5>Declaration</h5>
<div class="language">
<p class="aside-title">Swift</p>
<pre class="highlight"><code><span class="kd">public</span> <span class="n">convenience</span> <span class="nf">init</span><span class="p">?()</span></code></pre>
</div>
</div>
</li>
<li>
<div>
<a name="/s:s16IteratorProtocolP4next7ElementQzSgyF"></a>
<a name="//apple_ref/swift/Method/next()" class="dashAnchor"></a>
<h4>
<code>next()</code>
</h4>
</div>
<div class="abstract">
</div>
<div class="declaration">
<h5>Declaration</h5>
<div class="language">
<p class="aside-title">Swift</p>
<pre class="highlight"><code><span class="kd">public</span> <span class="kd">func</span> <span class="nf">next</span><span class="p">()</span> <span class="o">-&gt;</span> <span class="kt">UInt64</span><span class="p">?</span></code></pre>
</div>
</div>
</li>
</ul>
</div>
<div class="group">
<ul>
<li>
<div>
<a name="/s:12NumericAnnex6RandomC9XoroshiroC"></a>
<a name="//apple_ref/swift/Class/Xoroshiro" class="dashAnchor"></a>
<h4>
<code>Xoroshiro</code>
</h4>
</div>
<div class="abstract">
<p>A pseudo-random number generator (PRNG) that implements <code>xoroshiro128+</code>, a
successor to <code>xorshift128+</code> devised by S. Vigna and D. Blackman.</p>
<div class="aside aside-warning">
<p class="aside-title">Warning</p>
Once seeded from cryptographically secure random bytes, an
instance of <code>Random.Xoroshiro</code> generates high-quality random numbers but
is <em>not</em> a cryptographically secure PRNG.
</div>
<p>To generate random numbers, create your own instance of <code>Random.Xoroshiro</code>
with an internal state seeded from cryptographically secure random bytes:</p>
<pre class="highlight swift"><code><span class="k">let</span> <span class="nv">random</span> <span class="o">=</span> <span class="kt">Random</span><span class="o">.</span><span class="kt">Xoroshiro</span><span class="p">()</span><span class="o">!</span>
<span class="k">let</span> <span class="nv">x</span> <span class="o">=</span> <span class="n">random</span><span class="o">.</span><span class="nf">uniform</span><span class="p">()</span> <span class="k">as</span> <span class="kt">Int</span>
<span class="c1">// You can also pass the desired result type as an argument.</span>
<span class="k">let</span> <span class="nv">y</span> <span class="o">=</span> <span class="n">random</span><span class="o">.</span><span class="nf">uniform</span><span class="p">(</span><span class="kt">Int</span><span class="o">.</span><span class="k">self</span><span class="p">)</span>
<span class="k">if</span> <span class="n">x</span> <span class="o">&gt;</span> <span class="n">y</span> <span class="p">{</span>
<span class="nf">print</span><span class="p">(</span><span class="s">"Here's a random value between 0 and 42 (inclusive):"</span><span class="p">)</span>
<span class="nf">print</span><span class="p">(</span><span class="n">random</span><span class="o">.</span><span class="nf">uniform</span><span class="p">(</span><span class="nv">a</span><span class="p">:</span> <span class="mi">0</span><span class="p">,</span> <span class="nv">b</span><span class="p">:</span> <span class="mi">42</span><span class="p">))</span>
<span class="p">}</span> <span class="k">else</span> <span class="p">{</span>
<span class="nf">print</span><span class="p">(</span><span class="s">"Here's a random value between -42 and 0 (inclusive):"</span><span class="p">)</span>
<span class="nf">print</span><span class="p">(</span><span class="n">random</span><span class="o">.</span><span class="nf">uniform</span><span class="p">(</span><span class="nv">a</span><span class="p">:</span> <span class="o">-</span><span class="mi">42</span><span class="p">,</span> <span class="nv">b</span><span class="p">:</span> <span class="mi">0</span><span class="p">))</span>
<span class="p">}</span>
</code></pre>
<div class="aside aside-see-also">
<p class="aside-title">See also</p>
<code><a href="../Classes/Random.html">Random</a></code>, <code><a href="../Protocols/PRNG.html">PRNG</a></code>
</div>
<a href="../Classes/Random/Xoroshiro.html">See more…</a>
</div>
<div class="declaration">
<h5>Declaration</h5>
<div class="language">
<p class="aside-title">Swift</p>
<pre class="highlight"><code><span class="kd">public</span> <span class="kd">final</span> <span class="kd">class</span> <span class="kt">Xoroshiro</span> <span class="p">:</span> <span class="kt"><a href="../Protocols/PRNG.html">PRNG</a></span></code></pre>
</div>
</div>
</li>
</ul>
</div>
</div>
</section>
</article>
</div>
<footer>
<p>&copy; 2017 <a class="link" href="https://diploid.ca" target="_blank" rel="external">Xiaodi Wu</a>. All rights reserved. (Last updated: 2017-08-12)</p>
<p>Generated by <a href="https://github.com/realm/jazzy" target="_blank" rel="external">Jazzy</a> v0.8.3, a <a href="http://realm.io" target="_blank" rel="external">Realm</a> project.</p>
</footer>
</body>
</div>
</html>