| <!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/k_tanf.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>k_tanf.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="comment">/* origin: FreeBSD /usr/src/lib/msun/src/k_tan.c */ |
| /* |
| * ==================================================== |
| * Copyright 2004 Sun Microsystems, Inc. All Rights Reserved. |
| * |
| * Permission to use, copy, modify, and distribute this |
| * software is freely granted, provided that this notice |
| * is preserved. |
| * ==================================================== |
| */ |
| |
| /* |tan(x)/x - t(x)| < 2**-25.5 (~[-2e-08, 2e-08]). */ |
| </span><span class="kw">const </span>T: [f64; <span class="number">6</span>] = [ |
| <span class="number">0.333331395030791399758</span>, <span class="comment">/* 0x15554d3418c99f.0p-54 */ |
| </span><span class="number">0.133392002712976742718</span>, <span class="comment">/* 0x1112fd38999f72.0p-55 */ |
| </span><span class="number">0.0533812378445670393523</span>, <span class="comment">/* 0x1b54c91d865afe.0p-57 */ |
| </span><span class="number">0.0245283181166547278873</span>, <span class="comment">/* 0x191df3908c33ce.0p-58 */ |
| </span><span class="number">0.00297435743359967304927</span>, <span class="comment">/* 0x185dadfcecf44e.0p-61 */ |
| </span><span class="number">0.00946564784943673166728</span>, <span class="comment">/* 0x1362b9bf971bcd.0p-59 */ |
| </span>]; |
| |
| <span class="attribute">#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>k_tanf(x: f64, odd: bool) -> f32 { |
| <span class="kw">let </span>z = x * x; |
| <span class="comment">/* |
| * Split up the polynomial into small independent terms to give |
| * opportunities for parallel evaluation. The chosen splitting is |
| * micro-optimized for Athlons (XP, X64). It costs 2 multiplications |
| * relative to Horner's method on sequential machines. |
| * |
| * We add the small terms from lowest degree up for efficiency on |
| * non-sequential machines (the lowest degree terms tend to be ready |
| * earlier). Apart from this, we don't care about order of |
| * operations, and don't need to to care since we have precision to |
| * spare. However, the chosen splitting is good for accuracy too, |
| * and would give results as accurate as Horner's method if the |
| * small terms were added from highest degree down. |
| */ |
| </span><span class="kw">let </span><span class="kw-2">mut </span>r = T[<span class="number">4</span>] + z * T[<span class="number">5</span>]; |
| <span class="kw">let </span>t = T[<span class="number">2</span>] + z * T[<span class="number">3</span>]; |
| <span class="kw">let </span>w = z * z; |
| <span class="kw">let </span>s = z * x; |
| <span class="kw">let </span>u = T[<span class="number">0</span>] + z * T[<span class="number">1</span>]; |
| r = (x + s * u) + (s * w) * (t + w * r); |
| (<span class="kw">if </span>odd { -<span class="number">1. </span>/ r } <span class="kw">else </span>{ r }) <span class="kw">as </span>f32 |
| } |
| </code></pre></div> |
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