| <!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/sin.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>sin.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/s_sin.c */ |
| // |
| // ==================================================== |
| // Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
| // |
| // Developed at SunPro, a Sun Microsystems, Inc. business. |
| // Permission to use, copy, modify, and distribute this |
| // software is freely granted, provided that this notice |
| // is preserved. |
| // ==================================================== |
| |
| </span><span class="kw">use super</span>::{k_cos, k_sin, rem_pio2}; |
| |
| <span class="comment">// sin(x) |
| // Return sine function of x. |
| // |
| // kernel function: |
| // k_sin ... sine function on [-pi/4,pi/4] |
| // k_cos ... cose function on [-pi/4,pi/4] |
| // rem_pio2 ... argument reduction routine |
| // |
| // Method. |
| // Let S,C and T denote the sin, cos and tan respectively on |
| // [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2 |
| // in [-pi/4 , +pi/4], and let n = k mod 4. |
| // We have |
| // |
| // n sin(x) cos(x) tan(x) |
| // ---------------------------------------------------------- |
| // 0 S C T |
| // 1 C -S -1/T |
| // 2 -S -C T |
| // 3 -C S -1/T |
| // ---------------------------------------------------------- |
| // |
| // Special cases: |
| // Let trig be any of sin, cos, or tan. |
| // trig(+-INF) is NaN, with signals; |
| // trig(NaN) is that NaN; |
| // |
| // Accuracy: |
| // TRIG(x) returns trig(x) nearly rounded |
| </span><span class="attribute">#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)] |
| </span><span class="kw">pub fn </span>sin(x: f64) -> f64 { |
| <span class="kw">let </span>x1p120 = f64::from_bits(<span class="number">0x4770000000000000</span>); <span class="comment">// 0x1p120f === 2 ^ 120 |
| |
| /* High word of x. */ |
| </span><span class="kw">let </span>ix = (f64::to_bits(x) >> <span class="number">32</span>) <span class="kw">as </span>u32 & <span class="number">0x7fffffff</span>; |
| |
| <span class="comment">/* |x| ~< pi/4 */ |
| </span><span class="kw">if </span>ix <= <span class="number">0x3fe921fb </span>{ |
| <span class="kw">if </span>ix < <span class="number">0x3e500000 </span>{ |
| <span class="comment">/* |x| < 2**-26 */ |
| /* raise inexact if x != 0 and underflow if subnormal*/ |
| </span><span class="kw">if </span>ix < <span class="number">0x00100000 </span>{ |
| <span class="macro">force_eval!</span>(x / x1p120); |
| } <span class="kw">else </span>{ |
| <span class="macro">force_eval!</span>(x + x1p120); |
| } |
| <span class="kw">return </span>x; |
| } |
| <span class="kw">return </span>k_sin(x, <span class="number">0.0</span>, <span class="number">0</span>); |
| } |
| |
| <span class="comment">/* sin(Inf or NaN) is NaN */ |
| </span><span class="kw">if </span>ix >= <span class="number">0x7ff00000 </span>{ |
| <span class="kw">return </span>x - x; |
| } |
| |
| <span class="comment">/* argument reduction needed */ |
| </span><span class="kw">let </span>(n, y0, y1) = rem_pio2(x); |
| <span class="kw">match </span>n & <span class="number">3 </span>{ |
| <span class="number">0 </span>=> k_sin(y0, y1, <span class="number">1</span>), |
| <span class="number">1 </span>=> k_cos(y0, y1), |
| <span class="number">2 </span>=> -k_sin(y0, y1, <span class="number">1</span>), |
| <span class="kw">_ </span>=> -k_cos(y0, y1), |
| } |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>test_near_pi() { |
| <span class="kw">let </span>x = f64::from_bits(<span class="number">0x400921fb000FD5DD</span>); <span class="comment">// 3.141592026217707 |
| </span><span class="kw">let </span>sx = f64::from_bits(<span class="number">0x3ea50d15ced1a4a2</span>); <span class="comment">// 6.273720864039205e-7 |
| </span><span class="kw">let </span>result = sin(x); |
| <span class="attribute">#[cfg(all(target_arch = <span class="string">"x86"</span>, not(target_feature = <span class="string">"sse2"</span>)))] |
| </span><span class="kw">let </span>result = <span class="macro">force_eval!</span>(result); |
| <span class="macro">assert_eq!</span>(result, sx); |
| } |
| </code></pre></div> |
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