| <!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/atanf.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>atanf.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_atanf.c */ |
| /* |
| * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. |
| */ |
| /* |
| * ==================================================== |
| * 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 </span><span class="kw">super</span>::fabsf; |
| |
| <span class="kw">const </span>ATAN_HI: [f32; <span class="number">4</span>] = [ |
| <span class="number">4.6364760399e-01</span>, <span class="comment">/* atan(0.5)hi 0x3eed6338 */ |
| </span><span class="number">7.8539812565e-01</span>, <span class="comment">/* atan(1.0)hi 0x3f490fda */ |
| </span><span class="number">9.8279368877e-01</span>, <span class="comment">/* atan(1.5)hi 0x3f7b985e */ |
| </span><span class="number">1.5707962513e+00</span>, <span class="comment">/* atan(inf)hi 0x3fc90fda */ |
| </span>]; |
| |
| <span class="kw">const </span>ATAN_LO: [f32; <span class="number">4</span>] = [ |
| <span class="number">5.0121582440e-09</span>, <span class="comment">/* atan(0.5)lo 0x31ac3769 */ |
| </span><span class="number">3.7748947079e-08</span>, <span class="comment">/* atan(1.0)lo 0x33222168 */ |
| </span><span class="number">3.4473217170e-08</span>, <span class="comment">/* atan(1.5)lo 0x33140fb4 */ |
| </span><span class="number">7.5497894159e-08</span>, <span class="comment">/* atan(inf)lo 0x33a22168 */ |
| </span>]; |
| |
| <span class="kw">const </span>A_T: [f32; <span class="number">5</span>] = [ |
| <span class="number">3.3333328366e-01</span>, |
| -<span class="number">1.9999158382e-01</span>, |
| <span class="number">1.4253635705e-01</span>, |
| -<span class="number">1.0648017377e-01</span>, |
| <span class="number">6.1687607318e-02</span>, |
| ]; |
| |
| <span class="doccomment">/// Arctangent (f32) |
| /// |
| /// Computes the inverse tangent (arc tangent) of the input value. |
| /// Returns a value in radians, in the range of -pi/2 to pi/2. |
| </span><span class="attribute">#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)] |
| </span><span class="kw">pub fn </span>atanf(<span class="kw-2">mut </span>x: f32) -> f32 { |
| <span class="kw">let </span>x1p_120 = f32::from_bits(<span class="number">0x03800000</span>); <span class="comment">// 0x1p-120 === 2 ^ (-120) |
| |
| </span><span class="kw">let </span>z: f32; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>ix = x.to_bits(); |
| <span class="kw">let </span>sign = (ix >> <span class="number">31</span>) != <span class="number">0</span>; |
| ix &= <span class="number">0x7fffffff</span>; |
| |
| <span class="kw">if </span>ix >= <span class="number">0x4c800000 </span>{ |
| <span class="comment">/* if |x| >= 2**26 */ |
| </span><span class="kw">if </span>x.is_nan() { |
| <span class="kw">return </span>x; |
| } |
| z = <span class="macro">i!</span>(ATAN_HI, <span class="number">3</span>) + x1p_120; |
| <span class="kw">return if </span>sign { -z } <span class="kw">else </span>{ z }; |
| } |
| <span class="kw">let </span>id = <span class="kw">if </span>ix < <span class="number">0x3ee00000 </span>{ |
| <span class="comment">/* |x| < 0.4375 */ |
| </span><span class="kw">if </span>ix < <span class="number">0x39800000 </span>{ |
| <span class="comment">/* |x| < 2**-12 */ |
| </span><span class="kw">if </span>ix < <span class="number">0x00800000 </span>{ |
| <span class="comment">/* raise underflow for subnormal x */ |
| </span><span class="macro">force_eval!</span>(x * x); |
| } |
| <span class="kw">return </span>x; |
| } |
| -<span class="number">1 |
| </span>} <span class="kw">else </span>{ |
| x = fabsf(x); |
| <span class="kw">if </span>ix < <span class="number">0x3f980000 </span>{ |
| <span class="comment">/* |x| < 1.1875 */ |
| </span><span class="kw">if </span>ix < <span class="number">0x3f300000 </span>{ |
| <span class="comment">/* 7/16 <= |x| < 11/16 */ |
| </span>x = (<span class="number">2. </span>* x - <span class="number">1.</span>) / (<span class="number">2. </span>+ x); |
| <span class="number">0 |
| </span>} <span class="kw">else </span>{ |
| <span class="comment">/* 11/16 <= |x| < 19/16 */ |
| </span>x = (x - <span class="number">1.</span>) / (x + <span class="number">1.</span>); |
| <span class="number">1 |
| </span>} |
| } <span class="kw">else if </span>ix < <span class="number">0x401c0000 </span>{ |
| <span class="comment">/* |x| < 2.4375 */ |
| </span>x = (x - <span class="number">1.5</span>) / (<span class="number">1. </span>+ <span class="number">1.5 </span>* x); |
| <span class="number">2 |
| </span>} <span class="kw">else </span>{ |
| <span class="comment">/* 2.4375 <= |x| < 2**26 */ |
| </span>x = -<span class="number">1. </span>/ x; |
| <span class="number">3 |
| </span>} |
| }; |
| <span class="comment">/* end of argument reduction */ |
| </span>z = x * x; |
| <span class="kw">let </span>w = z * z; |
| <span class="comment">/* break sum from i=0 to 10 aT[i]z**(i+1) into odd and even poly */ |
| </span><span class="kw">let </span>s1 = z * (<span class="macro">i!</span>(A_T, <span class="number">0</span>) + w * (<span class="macro">i!</span>(A_T, <span class="number">2</span>) + w * <span class="macro">i!</span>(A_T, <span class="number">4</span>))); |
| <span class="kw">let </span>s2 = w * (<span class="macro">i!</span>(A_T, <span class="number">1</span>) + w * <span class="macro">i!</span>(A_T, <span class="number">3</span>)); |
| <span class="kw">if </span>id < <span class="number">0 </span>{ |
| <span class="kw">return </span>x - x * (s1 + s2); |
| } |
| <span class="kw">let </span>id = id <span class="kw">as </span>usize; |
| <span class="kw">let </span>z = <span class="macro">i!</span>(ATAN_HI, id) - ((x * (s1 + s2) - <span class="macro">i!</span>(ATAN_LO, id)) - x); |
| <span class="kw">if </span>sign { |
| -z |
| } <span class="kw">else </span>{ |
| z |
| } |
| } |
| </code></pre></div> |
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