| <!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/hypot.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>hypot.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="kw">use </span>core::f64; |
| |
| <span class="kw">use </span><span class="kw">super</span>::sqrt; |
| |
| <span class="kw">const </span>SPLIT: f64 = <span class="number">134217728. </span>+ <span class="number">1.</span>; <span class="comment">// 0x1p27 + 1 === (2 ^ 27) + 1 |
| |
| </span><span class="kw">fn </span>sq(x: f64) -> (f64, f64) { |
| <span class="kw">let </span>xh: f64; |
| <span class="kw">let </span>xl: f64; |
| <span class="kw">let </span>xc: f64; |
| |
| xc = x * SPLIT; |
| xh = x - xc + xc; |
| xl = x - xh; |
| <span class="kw">let </span>hi = x * x; |
| <span class="kw">let </span>lo = xh * xh - hi + <span class="number">2. </span>* xh * xl + xl * xl; |
| (hi, lo) |
| } |
| |
| <span class="attribute">#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)] |
| </span><span class="kw">pub fn </span>hypot(<span class="kw-2">mut </span>x: f64, <span class="kw-2">mut </span>y: f64) -> f64 { |
| <span class="kw">let </span>x1p700 = f64::from_bits(<span class="number">0x6bb0000000000000</span>); <span class="comment">// 0x1p700 === 2 ^ 700 |
| </span><span class="kw">let </span>x1p_700 = f64::from_bits(<span class="number">0x1430000000000000</span>); <span class="comment">// 0x1p-700 === 2 ^ -700 |
| |
| </span><span class="kw">let </span><span class="kw-2">mut </span>uxi = x.to_bits(); |
| <span class="kw">let </span><span class="kw-2">mut </span>uyi = y.to_bits(); |
| <span class="kw">let </span>uti; |
| <span class="kw">let </span>ex: i64; |
| <span class="kw">let </span>ey: i64; |
| <span class="kw">let </span><span class="kw-2">mut </span>z: f64; |
| |
| <span class="comment">/* arrange |x| >= |y| */ |
| </span>uxi &= -<span class="number">1i64 </span><span class="kw">as </span>u64 >> <span class="number">1</span>; |
| uyi &= -<span class="number">1i64 </span><span class="kw">as </span>u64 >> <span class="number">1</span>; |
| <span class="kw">if </span>uxi < uyi { |
| uti = uxi; |
| uxi = uyi; |
| uyi = uti; |
| } |
| |
| <span class="comment">/* special cases */ |
| </span>ex = (uxi >> <span class="number">52</span>) <span class="kw">as </span>i64; |
| ey = (uyi >> <span class="number">52</span>) <span class="kw">as </span>i64; |
| x = f64::from_bits(uxi); |
| y = f64::from_bits(uyi); |
| <span class="comment">/* note: hypot(inf,nan) == inf */ |
| </span><span class="kw">if </span>ey == <span class="number">0x7ff </span>{ |
| <span class="kw">return </span>y; |
| } |
| <span class="kw">if </span>ex == <span class="number">0x7ff </span>|| uyi == <span class="number">0 </span>{ |
| <span class="kw">return </span>x; |
| } |
| <span class="comment">/* note: hypot(x,y) ~= x + y*y/x/2 with inexact for small y/x */ |
| /* 64 difference is enough for ld80 double_t */ |
| </span><span class="kw">if </span>ex - ey > <span class="number">64 </span>{ |
| <span class="kw">return </span>x + y; |
| } |
| |
| <span class="comment">/* precise sqrt argument in nearest rounding mode without overflow */ |
| /* xh*xh must not overflow and xl*xl must not underflow in sq */ |
| </span>z = <span class="number">1.</span>; |
| <span class="kw">if </span>ex > <span class="number">0x3ff </span>+ <span class="number">510 </span>{ |
| z = x1p700; |
| x <span class="kw-2">*</span>= x1p_700; |
| y <span class="kw-2">*</span>= x1p_700; |
| } <span class="kw">else if </span>ey < <span class="number">0x3ff </span>- <span class="number">450 </span>{ |
| z = x1p_700; |
| x <span class="kw-2">*</span>= x1p700; |
| y <span class="kw-2">*</span>= x1p700; |
| } |
| <span class="kw">let </span>(hx, lx) = sq(x); |
| <span class="kw">let </span>(hy, ly) = sq(y); |
| z * sqrt(ly + lx + hy + hx) |
| } |
| </code></pre></div> |
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