<!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/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="../../../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="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="attr">#[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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