<!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 `/Users/erlendbasso/.cargo/registry/src/github.com-1ecc6299db9ec823/libm-0.2.6/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="../../../static.files/SourceSerif4-Regular-1f7d512b176f0f72.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../static.files/FiraSans-Regular-018c141bf0843ffd.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../static.files/FiraSans-Medium-8f9a781e4970d388.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../static.files/SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../static.files/SourceSerif4-Bold-124a1ca42af929b6.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../static.files/SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2"><link rel="stylesheet" href="../../../static.files/normalize-76eba96aa4d2e634.css"><link rel="stylesheet" href="../../../static.files/rustdoc-6827029ac823cab7.css" id="mainThemeStyle"><link rel="stylesheet" id="themeStyle" href="../../../static.files/light-ebce58d0a40c3431.css"><link rel="stylesheet" disabled href="../../../static.files/dark-f23faae4a2daf9a6.css"><link rel="stylesheet" disabled href="../../../static.files/ayu-8af5e100b21cd173.css"><script id="default-settings" ></script><script src="../../../static.files/storage-d43fa987303ecbbb.js"></script><script defer src="../../../static.files/source-script-5cf2e01a42cc9858.js"></script><script defer src="../../../source-files.js"></script><script defer src="../../../static.files/main-c55e1eb52e1886b4.js"></script><noscript><link rel="stylesheet" href="../../../static.files/noscript-13285aec31fa243e.css"></noscript><link rel="alternate icon" type="image/png" href="../../../static.files/favicon-16x16-8b506e7a72182f1c.png"><link rel="alternate icon" type="image/png" href="../../../static.files/favicon-32x32-422f7d1d52889060.png"><link rel="icon" type="image/svg+xml" href="../../../static.files/favicon-2c020d218678b618.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"></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../libm/index.html"><img class="rust-logo" src="../../../static.files/rust-logo-151179464ae7ed46.svg" alt="logo"></a><form class="search-form"><span></span><input class="search-input" name="search" aria-label="Run search in the documentation" 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="../../../static.files/wheel-5ec35bf9ca753509.svg"></a></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><a href="#1" id="1">1</a>
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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="attr">#[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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