| <!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 of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/libm-0.2.7/src/math/atanh.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>atanh.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../../normalize.css"><link rel="stylesheet" href="../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../ayu.css" disabled><link rel="stylesheet" href="../../../dark.css" disabled><link rel="stylesheet" href="../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../storage.js"></script><script defer src="../../../source-script.js"></script><script defer src="../../../source-files.js"></script><script defer src="../../../main.js"></script><noscript><link rel="stylesheet" href="../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../libm/index.html"><div class="logo-container"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../libm/index.html"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="kw">use </span><span class="kw">super</span>::log1p; |
| |
| <span class="comment">/* atanh(x) = log((1+x)/(1-x))/2 = log1p(2x/(1-x))/2 ~= x + x^3/3 + o(x^5) */ |
| </span><span class="doccomment">/// Inverse hyperbolic tangent (f64) |
| /// |
| /// Calculates the inverse hyperbolic tangent of `x`. |
| /// Is defined as `log((1+x)/(1-x))/2 = log1p(2x/(1-x))/2`. |
| </span><span class="attribute">#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)] |
| </span><span class="kw">pub fn </span>atanh(x: f64) -> f64 { |
| <span class="kw">let </span>u = x.to_bits(); |
| <span class="kw">let </span>e = ((u >> <span class="number">52</span>) <span class="kw">as </span>usize) & <span class="number">0x7ff</span>; |
| <span class="kw">let </span>sign = (u >> <span class="number">63</span>) != <span class="number">0</span>; |
| |
| <span class="comment">/* |x| */ |
| </span><span class="kw">let </span><span class="kw-2">mut </span>y = f64::from_bits(u & <span class="number">0x7fff_ffff_ffff_ffff</span>); |
| |
| <span class="kw">if </span>e < <span class="number">0x3ff </span>- <span class="number">1 </span>{ |
| <span class="kw">if </span>e < <span class="number">0x3ff </span>- <span class="number">32 </span>{ |
| <span class="comment">/* handle underflow */ |
| </span><span class="kw">if </span>e == <span class="number">0 </span>{ |
| <span class="macro">force_eval!</span>(y <span class="kw">as </span>f32); |
| } |
| } <span class="kw">else </span>{ |
| <span class="comment">/* |x| < 0.5, up to 1.7ulp error */ |
| </span>y = <span class="number">0.5 </span>* log1p(<span class="number">2.0 </span>* y + <span class="number">2.0 </span>* y * y / (<span class="number">1.0 </span>- y)); |
| } |
| } <span class="kw">else </span>{ |
| <span class="comment">/* avoid overflow */ |
| </span>y = <span class="number">0.5 </span>* log1p(<span class="number">2.0 </span>* (y / (<span class="number">1.0 </span>- y))); |
| } |
| |
| <span class="kw">if </span>sign { |
| -y |
| } <span class="kw">else </span>{ |
| y |
| } |
| } |
| </code></pre></div> |
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