| <!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/asinf.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>asinf.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/e_asinf.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::fabsf; |
| <span class="kw">use </span><span class="kw">super</span>::sqrt::sqrt; |
| |
| <span class="kw">const </span>PIO2: f64 = <span class="number">1.570796326794896558e+00</span>; |
| |
| <span class="comment">/* coefficients for R(x^2) */ |
| </span><span class="kw">const </span>P_S0: f32 = <span class="number">1.6666586697e-01</span>; |
| <span class="kw">const </span>P_S1: f32 = -<span class="number">4.2743422091e-02</span>; |
| <span class="kw">const </span>P_S2: f32 = -<span class="number">8.6563630030e-03</span>; |
| <span class="kw">const </span>Q_S1: f32 = -<span class="number">7.0662963390e-01</span>; |
| |
| <span class="kw">fn </span>r(z: f32) -> f32 { |
| <span class="kw">let </span>p = z * (P_S0 + z * (P_S1 + z * P_S2)); |
| <span class="kw">let </span>q = <span class="number">1. </span>+ z * Q_S1; |
| p / q |
| } |
| |
| <span class="doccomment">/// Arcsine (f32) |
| /// |
| /// Computes the inverse sine (arc sine) of the argument `x`. |
| /// Arguments to asin must be in the range -1 to 1. |
| /// Returns values 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>asinf(<span class="kw-2">mut </span>x: f32) -> f32 { |
| <span class="kw">let </span>x1p_120 = f64::from_bits(<span class="number">0x3870000000000000</span>); <span class="comment">// 0x1p-120 === 2 ^ (-120) |
| |
| </span><span class="kw">let </span>hx = x.to_bits(); |
| <span class="kw">let </span>ix = hx & <span class="number">0x7fffffff</span>; |
| |
| <span class="kw">if </span>ix >= <span class="number">0x3f800000 </span>{ |
| <span class="comment">/* |x| >= 1 */ |
| </span><span class="kw">if </span>ix == <span class="number">0x3f800000 </span>{ |
| <span class="comment">/* |x| == 1 */ |
| </span><span class="kw">return </span>((x <span class="kw">as </span>f64) * PIO2 + x1p_120) <span class="kw">as </span>f32; <span class="comment">/* asin(+-1) = +-pi/2 with inexact */ |
| </span>} |
| <span class="kw">return </span><span class="number">0. </span>/ (x - x); <span class="comment">/* asin(|x|>1) is NaN */ |
| </span>} |
| |
| <span class="kw">if </span>ix < <span class="number">0x3f000000 </span>{ |
| <span class="comment">/* |x| < 0.5 */ |
| /* if 0x1p-126 <= |x| < 0x1p-12, avoid raising underflow */ |
| </span><span class="kw">if </span>(ix < <span class="number">0x39800000</span>) && (ix >= <span class="number">0x00800000</span>) { |
| <span class="kw">return </span>x; |
| } |
| <span class="kw">return </span>x + x * r(x * x); |
| } |
| |
| <span class="comment">/* 1 > |x| >= 0.5 */ |
| </span><span class="kw">let </span>z = (<span class="number">1. </span>- fabsf(x)) * <span class="number">0.5</span>; |
| <span class="kw">let </span>s = sqrt(z <span class="kw">as </span>f64); |
| x = (PIO2 - <span class="number">2. </span>* (s + s * (r(z) <span class="kw">as </span>f64))) <span class="kw">as </span>f32; |
| <span class="kw">if </span>(hx >> <span class="number">31</span>) != <span class="number">0 </span>{ |
| -x |
| } <span class="kw">else </span>{ |
| x |
| } |
| } |
| </code></pre></div> |
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