<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source to the Rust file `/home/mrh/.cargo/registry/src/github.com-1ecc6299db9ec823/libm-0.1.4/src/math/acosh.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>acosh.rs.html -- source</title><link rel="stylesheet" type="text/css" href="../../../normalize.css"><link rel="stylesheet" type="text/css" href="../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../../dark.css"><link rel="stylesheet" type="text/css" href="../../../light.css" id="themeStyle"><script src="../../../storage.js"></script><noscript><link rel="stylesheet" href="../../../noscript.css"></noscript><link rel="shortcut icon" href="../../../favicon.ico"><style type="text/css">#crate-search{background-image:url("../../../down-arrow.svg");}</style></head><body class="rustdoc source"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">☰</div><a href='../../../libm/index.html'><div class='logo-container'><img src='../../../rust-logo.png' alt='logo'></div></a></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!"><img src="../../../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices"></div></div><script src="../../../theme.js"></script><nav class="sub"><form class="search-form js-only"><div class="search-container"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"></div><a id="settings-menu" href="../../../settings.html"><img src="../../../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><pre class="line-numbers"><span id="1"> 1</span>
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</pre><div class="example-wrap"><pre class="rust ">
<span class="kw">use</span> <span class="kw">super</span>::{<span class="ident">log</span>, <span class="ident">log1p</span>, <span class="ident">sqrt</span>};
<span class="kw">const</span> <span class="ident">LN2</span>: <span class="ident">f64</span> <span class="op">=</span> <span class="number">0.693147180559945309417232121458176568</span>; <span class="comment">/* 0x3fe62e42, 0xfefa39ef*/</span>
<span class="doccomment">/// Inverse hyperbolic cosine (f64)</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Calculates the inverse hyperbolic cosine of `x`.</span>
<span class="doccomment">/// Is defined as `log(x + sqrt(x*x-1))`.</span>
<span class="doccomment">/// `x` must be a number greater than or equal to 1.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">acosh</span>(<span class="ident">x</span>: <span class="ident">f64</span>) <span class="op">-</span><span class="op">></span> <span class="ident">f64</span> {
<span class="kw">let</span> <span class="ident">u</span> <span class="op">=</span> <span class="ident">x</span>.<span class="ident">to_bits</span>();
<span class="kw">let</span> <span class="ident">e</span> <span class="op">=</span> ((<span class="ident">u</span> <span class="op">></span><span class="op">></span> <span class="number">52</span>) <span class="kw">as</span> <span class="ident">usize</span>) <span class="op">&</span> <span class="number">0x7ff</span>;
<span class="comment">/* x < 1 domain error is handled in the called functions */</span>
<span class="kw">if</span> <span class="ident">e</span> <span class="op"><</span> <span class="number">0x3ff</span> <span class="op">+</span> <span class="number">1</span> {
<span class="comment">/* |x| < 2, up to 2ulp error in [1,1.125] */</span>
<span class="kw">return</span> <span class="ident">log1p</span>(<span class="ident">x</span> <span class="op">-</span> <span class="number">1.0</span> <span class="op">+</span> <span class="ident">sqrt</span>((<span class="ident">x</span> <span class="op">-</span> <span class="number">1.0</span>) <span class="op">*</span> (<span class="ident">x</span> <span class="op">-</span> <span class="number">1.0</span>) <span class="op">+</span> <span class="number">2.0</span> <span class="op">*</span> (<span class="ident">x</span> <span class="op">-</span> <span class="number">1.0</span>)));
}
<span class="kw">if</span> <span class="ident">e</span> <span class="op"><</span> <span class="number">0x3ff</span> <span class="op">+</span> <span class="number">26</span> {
<span class="comment">/* |x| < 0x1p26 */</span>
<span class="kw">return</span> <span class="ident">log</span>(<span class="number">2.0</span> <span class="op">*</span> <span class="ident">x</span> <span class="op">-</span> <span class="number">1.0</span> <span class="op">/</span> (<span class="ident">x</span> <span class="op">+</span> <span class="ident">sqrt</span>(<span class="ident">x</span> <span class="op">*</span> <span class="ident">x</span> <span class="op">-</span> <span class="number">1.0</span>)));
}
<span class="comment">/* |x| >= 0x1p26 or nan */</span>
<span class="kw">return</span> <span class="ident">log</span>(<span class="ident">x</span>) <span class="op">+</span> <span class="ident">LN2</span>;
}
</pre></div>
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