| <!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 `rand_distr/src/binomial.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>binomial.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" type="text/css" href="../../normalize.css"><link rel="stylesheet" type="text/css" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../ayu.css" disabled><link rel="stylesheet" type="text/css" href="../../dark.css" disabled><link rel="stylesheet" type="text/css" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script src="../../crates.js"></script><script defer src="../../main.js"></script><script defer src="../../source-script.js"></script><script defer src="../../source-files.js"></script> |
| <noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="shortcut icon" href="https://www.rust-lang.org/favicon.ico"></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"><div class="sidebar-menu" role="button">☰</div><a class="sidebar-logo" href="../../rand_distr/index.html"><div class="logo-container"><img src="https://www.rust-lang.org/logos/rust-logo-128x128-blk.png" alt="logo"></div> |
| </a></nav><main><div class="width-limiter"><div class="sub-container"><a class="sub-logo-container" href="../../rand_distr/index.html"><img src="https://www.rust-lang.org/logos/rust-logo-128x128-blk.png" alt="logo"></a><nav class="sub"><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!" aria-haspopup="menu" title="themes"><img width="18" height="18" alt="Pick another theme!" src="../../brush.svg"></button><div id="theme-choices" role="menu"></div></div><form class="search-form"><div class="search-container"><div> |
| <input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"></div><button type="button" id="help-button" title="help">?</button><a id="settings-menu" href="../../settings.html" title="settings"><img width="18" height="18" alt="Change settings" src="../../wheel.svg"></a></div></form></nav></div><section id="main-content" class="content"><div class="example-wrap"><pre class="line-numbers"><span id="1"> 1</span> |
| <span id="2"> 2</span> |
| <span id="3"> 3</span> |
| <span id="4"> 4</span> |
| <span id="5"> 5</span> |
| <span id="6"> 6</span> |
| <span id="7"> 7</span> |
| <span id="8"> 8</span> |
| <span id="9"> 9</span> |
| <span id="10"> 10</span> |
| <span id="11"> 11</span> |
| <span id="12"> 12</span> |
| <span id="13"> 13</span> |
| <span id="14"> 14</span> |
| <span id="15"> 15</span> |
| <span id="16"> 16</span> |
| <span id="17"> 17</span> |
| <span id="18"> 18</span> |
| <span id="19"> 19</span> |
| <span id="20"> 20</span> |
| <span id="21"> 21</span> |
| <span id="22"> 22</span> |
| <span id="23"> 23</span> |
| <span id="24"> 24</span> |
| <span id="25"> 25</span> |
| <span id="26"> 26</span> |
| <span id="27"> 27</span> |
| <span id="28"> 28</span> |
| <span id="29"> 29</span> |
| <span id="30"> 30</span> |
| <span id="31"> 31</span> |
| <span id="32"> 32</span> |
| <span id="33"> 33</span> |
| <span id="34"> 34</span> |
| <span id="35"> 35</span> |
| <span id="36"> 36</span> |
| <span id="37"> 37</span> |
| <span id="38"> 38</span> |
| <span id="39"> 39</span> |
| <span id="40"> 40</span> |
| <span id="41"> 41</span> |
| <span id="42"> 42</span> |
| <span id="43"> 43</span> |
| <span id="44"> 44</span> |
| <span id="45"> 45</span> |
| <span id="46"> 46</span> |
| <span id="47"> 47</span> |
| <span id="48"> 48</span> |
| <span id="49"> 49</span> |
| <span id="50"> 50</span> |
| <span id="51"> 51</span> |
| <span id="52"> 52</span> |
| <span id="53"> 53</span> |
| <span id="54"> 54</span> |
| <span id="55"> 55</span> |
| <span id="56"> 56</span> |
| <span id="57"> 57</span> |
| <span id="58"> 58</span> |
| <span id="59"> 59</span> |
| <span id="60"> 60</span> |
| <span id="61"> 61</span> |
| <span id="62"> 62</span> |
| <span id="63"> 63</span> |
| <span id="64"> 64</span> |
| <span id="65"> 65</span> |
| <span id="66"> 66</span> |
| <span id="67"> 67</span> |
| <span id="68"> 68</span> |
| <span id="69"> 69</span> |
| <span id="70"> 70</span> |
| <span id="71"> 71</span> |
| <span id="72"> 72</span> |
| <span id="73"> 73</span> |
| <span id="74"> 74</span> |
| <span id="75"> 75</span> |
| <span id="76"> 76</span> |
| <span id="77"> 77</span> |
| <span id="78"> 78</span> |
| <span id="79"> 79</span> |
| <span id="80"> 80</span> |
| <span id="81"> 81</span> |
| <span id="82"> 82</span> |
| <span id="83"> 83</span> |
| <span id="84"> 84</span> |
| <span id="85"> 85</span> |
| <span id="86"> 86</span> |
| <span id="87"> 87</span> |
| <span id="88"> 88</span> |
| <span id="89"> 89</span> |
| <span id="90"> 90</span> |
| <span id="91"> 91</span> |
| <span id="92"> 92</span> |
| <span id="93"> 93</span> |
| <span id="94"> 94</span> |
| <span id="95"> 95</span> |
| <span id="96"> 96</span> |
| <span id="97"> 97</span> |
| <span id="98"> 98</span> |
| <span id="99"> 99</span> |
| <span id="100">100</span> |
| <span id="101">101</span> |
| <span id="102">102</span> |
| <span id="103">103</span> |
| <span id="104">104</span> |
| <span id="105">105</span> |
| <span id="106">106</span> |
| <span id="107">107</span> |
| <span id="108">108</span> |
| <span id="109">109</span> |
| <span id="110">110</span> |
| <span id="111">111</span> |
| <span id="112">112</span> |
| <span id="113">113</span> |
| <span id="114">114</span> |
| <span id="115">115</span> |
| <span id="116">116</span> |
| <span id="117">117</span> |
| <span id="118">118</span> |
| <span id="119">119</span> |
| <span id="120">120</span> |
| <span id="121">121</span> |
| <span id="122">122</span> |
| <span id="123">123</span> |
| <span id="124">124</span> |
| <span id="125">125</span> |
| <span id="126">126</span> |
| <span id="127">127</span> |
| <span id="128">128</span> |
| <span id="129">129</span> |
| <span id="130">130</span> |
| <span id="131">131</span> |
| <span id="132">132</span> |
| <span id="133">133</span> |
| <span id="134">134</span> |
| <span id="135">135</span> |
| <span id="136">136</span> |
| <span id="137">137</span> |
| <span id="138">138</span> |
| <span id="139">139</span> |
| <span id="140">140</span> |
| <span id="141">141</span> |
| <span id="142">142</span> |
| <span id="143">143</span> |
| <span id="144">144</span> |
| <span id="145">145</span> |
| <span id="146">146</span> |
| <span id="147">147</span> |
| <span id="148">148</span> |
| <span id="149">149</span> |
| <span id="150">150</span> |
| <span id="151">151</span> |
| <span id="152">152</span> |
| <span id="153">153</span> |
| <span id="154">154</span> |
| <span id="155">155</span> |
| <span id="156">156</span> |
| <span id="157">157</span> |
| <span id="158">158</span> |
| <span id="159">159</span> |
| <span id="160">160</span> |
| <span id="161">161</span> |
| <span id="162">162</span> |
| <span id="163">163</span> |
| <span id="164">164</span> |
| <span id="165">165</span> |
| <span id="166">166</span> |
| <span id="167">167</span> |
| <span id="168">168</span> |
| <span id="169">169</span> |
| <span id="170">170</span> |
| <span id="171">171</span> |
| <span id="172">172</span> |
| <span id="173">173</span> |
| <span id="174">174</span> |
| <span id="175">175</span> |
| <span id="176">176</span> |
| <span id="177">177</span> |
| <span id="178">178</span> |
| <span id="179">179</span> |
| <span id="180">180</span> |
| <span id="181">181</span> |
| <span id="182">182</span> |
| <span id="183">183</span> |
| <span id="184">184</span> |
| <span id="185">185</span> |
| <span id="186">186</span> |
| <span id="187">187</span> |
| <span id="188">188</span> |
| <span id="189">189</span> |
| <span id="190">190</span> |
| <span id="191">191</span> |
| <span id="192">192</span> |
| <span id="193">193</span> |
| <span id="194">194</span> |
| <span id="195">195</span> |
| <span id="196">196</span> |
| <span id="197">197</span> |
| <span id="198">198</span> |
| <span id="199">199</span> |
| <span id="200">200</span> |
| <span id="201">201</span> |
| <span id="202">202</span> |
| <span id="203">203</span> |
| <span id="204">204</span> |
| <span id="205">205</span> |
| <span id="206">206</span> |
| <span id="207">207</span> |
| <span id="208">208</span> |
| <span id="209">209</span> |
| <span id="210">210</span> |
| <span id="211">211</span> |
| <span id="212">212</span> |
| <span id="213">213</span> |
| <span id="214">214</span> |
| <span id="215">215</span> |
| <span id="216">216</span> |
| <span id="217">217</span> |
| <span id="218">218</span> |
| <span id="219">219</span> |
| <span id="220">220</span> |
| <span id="221">221</span> |
| <span id="222">222</span> |
| <span id="223">223</span> |
| <span id="224">224</span> |
| <span id="225">225</span> |
| <span id="226">226</span> |
| <span id="227">227</span> |
| <span id="228">228</span> |
| <span id="229">229</span> |
| <span id="230">230</span> |
| <span id="231">231</span> |
| <span id="232">232</span> |
| <span id="233">233</span> |
| <span id="234">234</span> |
| <span id="235">235</span> |
| <span id="236">236</span> |
| <span id="237">237</span> |
| <span id="238">238</span> |
| <span id="239">239</span> |
| <span id="240">240</span> |
| <span id="241">241</span> |
| <span id="242">242</span> |
| <span id="243">243</span> |
| <span id="244">244</span> |
| <span id="245">245</span> |
| <span id="246">246</span> |
| <span id="247">247</span> |
| <span id="248">248</span> |
| <span id="249">249</span> |
| <span id="250">250</span> |
| <span id="251">251</span> |
| <span id="252">252</span> |
| <span id="253">253</span> |
| <span id="254">254</span> |
| <span id="255">255</span> |
| <span id="256">256</span> |
| <span id="257">257</span> |
| <span id="258">258</span> |
| <span id="259">259</span> |
| <span id="260">260</span> |
| <span id="261">261</span> |
| <span id="262">262</span> |
| <span id="263">263</span> |
| <span id="264">264</span> |
| <span id="265">265</span> |
| <span id="266">266</span> |
| <span id="267">267</span> |
| <span id="268">268</span> |
| <span id="269">269</span> |
| <span id="270">270</span> |
| <span id="271">271</span> |
| <span id="272">272</span> |
| <span id="273">273</span> |
| <span id="274">274</span> |
| <span id="275">275</span> |
| <span id="276">276</span> |
| <span id="277">277</span> |
| <span id="278">278</span> |
| <span id="279">279</span> |
| <span id="280">280</span> |
| <span id="281">281</span> |
| <span id="282">282</span> |
| <span id="283">283</span> |
| <span id="284">284</span> |
| <span id="285">285</span> |
| <span id="286">286</span> |
| <span id="287">287</span> |
| <span id="288">288</span> |
| <span id="289">289</span> |
| <span id="290">290</span> |
| <span id="291">291</span> |
| <span id="292">292</span> |
| <span id="293">293</span> |
| <span id="294">294</span> |
| <span id="295">295</span> |
| <span id="296">296</span> |
| <span id="297">297</span> |
| <span id="298">298</span> |
| <span id="299">299</span> |
| <span id="300">300</span> |
| <span id="301">301</span> |
| <span id="302">302</span> |
| <span id="303">303</span> |
| <span id="304">304</span> |
| <span id="305">305</span> |
| <span id="306">306</span> |
| <span id="307">307</span> |
| <span id="308">308</span> |
| <span id="309">309</span> |
| <span id="310">310</span> |
| <span id="311">311</span> |
| <span id="312">312</span> |
| <span id="313">313</span> |
| <span id="314">314</span> |
| <span id="315">315</span> |
| <span id="316">316</span> |
| <span id="317">317</span> |
| <span id="318">318</span> |
| <span id="319">319</span> |
| <span id="320">320</span> |
| <span id="321">321</span> |
| <span id="322">322</span> |
| <span id="323">323</span> |
| <span id="324">324</span> |
| <span id="325">325</span> |
| <span id="326">326</span> |
| <span id="327">327</span> |
| <span id="328">328</span> |
| <span id="329">329</span> |
| <span id="330">330</span> |
| <span id="331">331</span> |
| <span id="332">332</span> |
| <span id="333">333</span> |
| <span id="334">334</span> |
| <span id="335">335</span> |
| <span id="336">336</span> |
| <span id="337">337</span> |
| <span id="338">338</span> |
| <span id="339">339</span> |
| <span id="340">340</span> |
| <span id="341">341</span> |
| <span id="342">342</span> |
| <span id="343">343</span> |
| <span id="344">344</span> |
| <span id="345">345</span> |
| <span id="346">346</span> |
| <span id="347">347</span> |
| <span id="348">348</span> |
| <span id="349">349</span> |
| <span id="350">350</span> |
| </pre><pre class="rust"><code><span class="comment">// Copyright 2018 Developers of the Rand project.</span> |
| <span class="comment">// Copyright 2016-2017 The Rust Project Developers.</span> |
| <span class="comment">//</span> |
| <span class="comment">// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or</span> |
| <span class="comment">// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license</span> |
| <span class="comment">// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your</span> |
| <span class="comment">// option. This file may not be copied, modified, or distributed</span> |
| <span class="comment">// except according to those terms.</span> |
| |
| <span class="doccomment">//! The binomial distribution.</span> |
| |
| <span class="kw">use</span> <span class="kw">crate</span>::{<span class="ident">Distribution</span>, <span class="ident">Uniform</span>}; |
| <span class="kw">use</span> <span class="ident">rand::Rng</span>; |
| <span class="kw">use</span> <span class="ident">core::fmt</span>; |
| <span class="kw">use</span> <span class="ident">core::cmp::Ordering</span>; |
| <span class="attribute">#[<span class="ident">allow</span>(<span class="ident">unused_imports</span>)]</span> |
| <span class="kw">use</span> <span class="ident">num_traits::Float</span>; |
| |
| <span class="doccomment">/// The binomial distribution `Binomial(n, p)`.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// This distribution has density function:</span> |
| <span class="doccomment">/// `f(k) = n!/(k! (n-k)!) p^k (1-p)^(n-k)` for `k >= 0`.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// # Example</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// ```</span> |
| <span class="doccomment">/// use rand_distr::{Binomial, Distribution};</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// let bin = Binomial::new(20, 0.3).unwrap();</span> |
| <span class="doccomment">/// let v = bin.sample(&mut rand::thread_rng());</span> |
| <span class="doccomment">/// println!("{} is from a binomial distribution", v);</span> |
| <span class="doccomment">/// ```</span> |
| <span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Copy</span>, <span class="ident">Debug</span>)]</span> |
| <span class="attribute">#[<span class="ident">cfg_attr</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"serde1"</span>, <span class="ident">derive</span>(<span class="ident">serde::Serialize</span>, <span class="ident">serde::Deserialize</span>))]</span> |
| <span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Binomial</span> { |
| <span class="doccomment">/// Number of trials.</span> |
| <span class="ident">n</span>: <span class="ident">u64</span>, |
| <span class="doccomment">/// Probability of success.</span> |
| <span class="ident">p</span>: <span class="ident">f64</span>, |
| } |
| |
| <span class="doccomment">/// Error type returned from `Binomial::new`.</span> |
| <span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Copy</span>, <span class="ident">Debug</span>, <span class="ident">PartialEq</span>, <span class="ident">Eq</span>)]</span> |
| <span class="kw">pub</span> <span class="kw">enum</span> <span class="ident">Error</span> { |
| <span class="doccomment">/// `p < 0` or `nan`.</span> |
| <span class="ident">ProbabilityTooSmall</span>, |
| <span class="doccomment">/// `p > 1`.</span> |
| <span class="ident">ProbabilityTooLarge</span>, |
| } |
| |
| <span class="kw">impl</span> <span class="ident">fmt::Display</span> <span class="kw">for</span> <span class="ident">Error</span> { |
| <span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&mut</span> <span class="ident">fmt::Formatter</span><span class="op"><</span><span class="lifetime">'_</span><span class="op">></span>) -> <span class="ident">fmt::Result</span> { |
| <span class="ident">f</span>.<span class="ident">write_str</span>(<span class="kw">match</span> <span class="self">self</span> { |
| <span class="ident">Error::ProbabilityTooSmall</span> => <span class="string">"p < 0 or is NaN in binomial distribution"</span>, |
| <span class="ident">Error::ProbabilityTooLarge</span> => <span class="string">"p > 1 in binomial distribution"</span>, |
| }) |
| } |
| } |
| |
| <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"std"</span>)]</span> |
| <span class="attribute">#[<span class="ident">cfg_attr</span>(<span class="ident">doc_cfg</span>, <span class="ident">doc</span>(<span class="ident">cfg</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"std"</span>)))]</span> |
| <span class="kw">impl</span> <span class="ident">std::error::Error</span> <span class="kw">for</span> <span class="ident">Error</span> {} |
| |
| <span class="kw">impl</span> <span class="ident">Binomial</span> { |
| <span class="doccomment">/// Construct a new `Binomial` with the given shape parameters `n` (number</span> |
| <span class="doccomment">/// of trials) and `p` (probability of success).</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new</span>(<span class="ident">n</span>: <span class="ident">u64</span>, <span class="ident">p</span>: <span class="ident">f64</span>) -> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">Binomial</span>, <span class="ident">Error</span><span class="op">></span> { |
| <span class="kw">if</span> <span class="op">!</span>(<span class="ident">p</span> <span class="op">></span><span class="op">=</span> <span class="number">0.0</span>) { |
| <span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::ProbabilityTooSmall</span>); |
| } |
| <span class="kw">if</span> <span class="op">!</span>(<span class="ident">p</span> <span class="op"><</span><span class="op">=</span> <span class="number">1.0</span>) { |
| <span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::ProbabilityTooLarge</span>); |
| } |
| <span class="prelude-val">Ok</span>(<span class="ident">Binomial</span> { <span class="ident">n</span>, <span class="ident">p</span> }) |
| } |
| } |
| |
| <span class="doccomment">/// Convert a `f64` to an `i64`, panicking on overflow.</span> |
| <span class="kw">fn</span> <span class="ident">f64_to_i64</span>(<span class="ident">x</span>: <span class="ident">f64</span>) -> <span class="ident">i64</span> { |
| <span class="macro">assert!</span>(<span class="ident">x</span> <span class="op"><</span> (<span class="ident">core::i64::MAX</span> <span class="kw">as</span> <span class="ident">f64</span>)); |
| <span class="ident">x</span> <span class="kw">as</span> <span class="ident">i64</span> |
| } |
| |
| <span class="kw">impl</span> <span class="ident">Distribution</span><span class="op"><</span><span class="ident">u64</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Binomial</span> { |
| <span class="attribute">#[<span class="ident">allow</span>(<span class="ident">clippy::many_single_char_names</span>)]</span> <span class="comment">// Same names as in the reference.</span> |
| <span class="kw">fn</span> <span class="ident">sample</span><span class="op"><</span><span class="ident">R</span>: <span class="ident">Rng</span> <span class="op">+</span> <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">rng</span>: <span class="kw-2">&mut</span> <span class="ident">R</span>) -> <span class="ident">u64</span> { |
| <span class="comment">// Handle these values directly.</span> |
| <span class="kw">if</span> <span class="self">self</span>.<span class="ident">p</span> <span class="op">==</span> <span class="number">0.0</span> { |
| <span class="kw">return</span> <span class="number">0</span>; |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="self">self</span>.<span class="ident">p</span> <span class="op">==</span> <span class="number">1.0</span> { |
| <span class="kw">return</span> <span class="self">self</span>.<span class="ident">n</span>; |
| } |
| |
| <span class="comment">// The binomial distribution is symmetrical with respect to p -> 1-p,</span> |
| <span class="comment">// k -> n-k switch p so that it is less than 0.5 - this allows for lower</span> |
| <span class="comment">// expected values we will just invert the result at the end</span> |
| <span class="kw">let</span> <span class="ident">p</span> <span class="op">=</span> <span class="kw">if</span> <span class="self">self</span>.<span class="ident">p</span> <span class="op"><</span><span class="op">=</span> <span class="number">0.5</span> { <span class="self">self</span>.<span class="ident">p</span> } <span class="kw">else</span> { <span class="number">1.0</span> <span class="op">-</span> <span class="self">self</span>.<span class="ident">p</span> }; |
| |
| <span class="kw">let</span> <span class="ident">result</span>; |
| <span class="kw">let</span> <span class="ident">q</span> <span class="op">=</span> <span class="number">1.</span> <span class="op">-</span> <span class="ident">p</span>; |
| |
| <span class="comment">// For small n * min(p, 1 - p), the BINV algorithm based on the inverse</span> |
| <span class="comment">// transformation of the binomial distribution is efficient. Otherwise,</span> |
| <span class="comment">// the BTPE algorithm is used.</span> |
| <span class="comment">//</span> |
| <span class="comment">// Voratas Kachitvichyanukul and Bruce W. Schmeiser. 1988. Binomial</span> |
| <span class="comment">// random variate generation. Commun. ACM 31, 2 (February 1988),</span> |
| <span class="comment">// 216-222. http://dx.doi.org/10.1145/42372.42381</span> |
| |
| <span class="comment">// Threshold for preferring the BINV algorithm. The paper suggests 10,</span> |
| <span class="comment">// Ranlib uses 30, and GSL uses 14.</span> |
| <span class="kw">const</span> <span class="ident">BINV_THRESHOLD</span>: <span class="ident">f64</span> <span class="op">=</span> <span class="number">10.</span>; |
| |
| <span class="kw">if</span> (<span class="self">self</span>.<span class="ident">n</span> <span class="kw">as</span> <span class="ident">f64</span>) <span class="op">*</span> <span class="ident">p</span> <span class="op"><</span> <span class="ident">BINV_THRESHOLD</span> <span class="op">&&</span> <span class="self">self</span>.<span class="ident">n</span> <span class="op"><</span><span class="op">=</span> (<span class="ident">core::i32::MAX</span> <span class="kw">as</span> <span class="ident">u64</span>) { |
| <span class="comment">// Use the BINV algorithm.</span> |
| <span class="kw">let</span> <span class="ident">s</span> <span class="op">=</span> <span class="ident">p</span> <span class="op">/</span> <span class="ident">q</span>; |
| <span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> ((<span class="self">self</span>.<span class="ident">n</span> <span class="op">+</span> <span class="number">1</span>) <span class="kw">as</span> <span class="ident">f64</span>) <span class="op">*</span> <span class="ident">s</span>; |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">r</span> <span class="op">=</span> <span class="ident">q</span>.<span class="ident">powi</span>(<span class="self">self</span>.<span class="ident">n</span> <span class="kw">as</span> <span class="ident">i32</span>); |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">u</span>: <span class="ident">f64</span> <span class="op">=</span> <span class="ident">rng</span>.<span class="ident">gen</span>(); |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">x</span> <span class="op">=</span> <span class="number">0</span>; |
| <span class="kw">while</span> <span class="ident">u</span> <span class="op">></span> <span class="ident">r</span> <span class="kw">as</span> <span class="ident">f64</span> { |
| <span class="ident">u</span> <span class="op">-</span><span class="op">=</span> <span class="ident">r</span>; |
| <span class="ident">x</span> <span class="op">+</span><span class="op">=</span> <span class="number">1</span>; |
| <span class="ident">r</span> <span class="kw-2">*</span><span class="op">=</span> <span class="ident">a</span> <span class="op">/</span> (<span class="ident">x</span> <span class="kw">as</span> <span class="ident">f64</span>) <span class="op">-</span> <span class="ident">s</span>; |
| } |
| <span class="ident">result</span> <span class="op">=</span> <span class="ident">x</span>; |
| } <span class="kw">else</span> { |
| <span class="comment">// Use the BTPE algorithm.</span> |
| |
| <span class="comment">// Threshold for using the squeeze algorithm. This can be freely</span> |
| <span class="comment">// chosen based on performance. Ranlib and GSL use 20.</span> |
| <span class="kw">const</span> <span class="ident">SQUEEZE_THRESHOLD</span>: <span class="ident">i64</span> <span class="op">=</span> <span class="number">20</span>; |
| |
| <span class="comment">// Step 0: Calculate constants as functions of `n` and `p`.</span> |
| <span class="kw">let</span> <span class="ident">n</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">n</span> <span class="kw">as</span> <span class="ident">f64</span>; |
| <span class="kw">let</span> <span class="ident">np</span> <span class="op">=</span> <span class="ident">n</span> <span class="op">*</span> <span class="ident">p</span>; |
| <span class="kw">let</span> <span class="ident">npq</span> <span class="op">=</span> <span class="ident">np</span> <span class="op">*</span> <span class="ident">q</span>; |
| <span class="kw">let</span> <span class="ident">f_m</span> <span class="op">=</span> <span class="ident">np</span> <span class="op">+</span> <span class="ident">p</span>; |
| <span class="kw">let</span> <span class="ident">m</span> <span class="op">=</span> <span class="ident">f64_to_i64</span>(<span class="ident">f_m</span>); |
| <span class="comment">// radius of triangle region, since height=1 also area of region</span> |
| <span class="kw">let</span> <span class="ident">p1</span> <span class="op">=</span> (<span class="number">2.195</span> <span class="op">*</span> <span class="ident">npq</span>.<span class="ident">sqrt</span>() <span class="op">-</span> <span class="number">4.6</span> <span class="op">*</span> <span class="ident">q</span>).<span class="ident">floor</span>() <span class="op">+</span> <span class="number">0.5</span>; |
| <span class="comment">// tip of triangle</span> |
| <span class="kw">let</span> <span class="ident">x_m</span> <span class="op">=</span> (<span class="ident">m</span> <span class="kw">as</span> <span class="ident">f64</span>) <span class="op">+</span> <span class="number">0.5</span>; |
| <span class="comment">// left edge of triangle</span> |
| <span class="kw">let</span> <span class="ident">x_l</span> <span class="op">=</span> <span class="ident">x_m</span> <span class="op">-</span> <span class="ident">p1</span>; |
| <span class="comment">// right edge of triangle</span> |
| <span class="kw">let</span> <span class="ident">x_r</span> <span class="op">=</span> <span class="ident">x_m</span> <span class="op">+</span> <span class="ident">p1</span>; |
| <span class="kw">let</span> <span class="ident">c</span> <span class="op">=</span> <span class="number">0.134</span> <span class="op">+</span> <span class="number">20.5</span> <span class="op">/</span> (<span class="number">15.3</span> <span class="op">+</span> (<span class="ident">m</span> <span class="kw">as</span> <span class="ident">f64</span>)); |
| <span class="comment">// p1 + area of parallelogram region</span> |
| <span class="kw">let</span> <span class="ident">p2</span> <span class="op">=</span> <span class="ident">p1</span> <span class="op">*</span> (<span class="number">1.</span> <span class="op">+</span> <span class="number">2.</span> <span class="op">*</span> <span class="ident">c</span>); |
| |
| <span class="kw">fn</span> <span class="ident">lambda</span>(<span class="ident">a</span>: <span class="ident">f64</span>) -> <span class="ident">f64</span> { |
| <span class="ident">a</span> <span class="op">*</span> (<span class="number">1.</span> <span class="op">+</span> <span class="number">0.5</span> <span class="op">*</span> <span class="ident">a</span>) |
| } |
| |
| <span class="kw">let</span> <span class="ident">lambda_l</span> <span class="op">=</span> <span class="ident">lambda</span>((<span class="ident">f_m</span> <span class="op">-</span> <span class="ident">x_l</span>) <span class="op">/</span> (<span class="ident">f_m</span> <span class="op">-</span> <span class="ident">x_l</span> <span class="op">*</span> <span class="ident">p</span>)); |
| <span class="kw">let</span> <span class="ident">lambda_r</span> <span class="op">=</span> <span class="ident">lambda</span>((<span class="ident">x_r</span> <span class="op">-</span> <span class="ident">f_m</span>) <span class="op">/</span> (<span class="ident">x_r</span> <span class="op">*</span> <span class="ident">q</span>)); |
| <span class="comment">// p1 + area of left tail</span> |
| <span class="kw">let</span> <span class="ident">p3</span> <span class="op">=</span> <span class="ident">p2</span> <span class="op">+</span> <span class="ident">c</span> <span class="op">/</span> <span class="ident">lambda_l</span>; |
| <span class="comment">// p1 + area of right tail</span> |
| <span class="kw">let</span> <span class="ident">p4</span> <span class="op">=</span> <span class="ident">p3</span> <span class="op">+</span> <span class="ident">c</span> <span class="op">/</span> <span class="ident">lambda_r</span>; |
| |
| <span class="comment">// return value</span> |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">y</span>: <span class="ident">i64</span>; |
| |
| <span class="kw">let</span> <span class="ident">gen_u</span> <span class="op">=</span> <span class="ident">Uniform::new</span>(<span class="number">0.</span>, <span class="ident">p4</span>); |
| <span class="kw">let</span> <span class="ident">gen_v</span> <span class="op">=</span> <span class="ident">Uniform::new</span>(<span class="number">0.</span>, <span class="number">1.</span>); |
| |
| <span class="kw">loop</span> { |
| <span class="comment">// Step 1: Generate `u` for selecting the region. If region 1 is</span> |
| <span class="comment">// selected, generate a triangularly distributed variate.</span> |
| <span class="kw">let</span> <span class="ident">u</span> <span class="op">=</span> <span class="ident">gen_u</span>.<span class="ident">sample</span>(<span class="ident">rng</span>); |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">v</span> <span class="op">=</span> <span class="ident">gen_v</span>.<span class="ident">sample</span>(<span class="ident">rng</span>); |
| <span class="kw">if</span> <span class="op">!</span>(<span class="ident">u</span> <span class="op">></span> <span class="ident">p1</span>) { |
| <span class="ident">y</span> <span class="op">=</span> <span class="ident">f64_to_i64</span>(<span class="ident">x_m</span> <span class="op">-</span> <span class="ident">p1</span> <span class="op">*</span> <span class="ident">v</span> <span class="op">+</span> <span class="ident">u</span>); |
| <span class="kw">break</span>; |
| } |
| |
| <span class="kw">if</span> <span class="op">!</span>(<span class="ident">u</span> <span class="op">></span> <span class="ident">p2</span>) { |
| <span class="comment">// Step 2: Region 2, parallelograms. Check if region 2 is</span> |
| <span class="comment">// used. If so, generate `y`.</span> |
| <span class="kw">let</span> <span class="ident">x</span> <span class="op">=</span> <span class="ident">x_l</span> <span class="op">+</span> (<span class="ident">u</span> <span class="op">-</span> <span class="ident">p1</span>) <span class="op">/</span> <span class="ident">c</span>; |
| <span class="ident">v</span> <span class="op">=</span> <span class="ident">v</span> <span class="op">*</span> <span class="ident">c</span> <span class="op">+</span> <span class="number">1.0</span> <span class="op">-</span> (<span class="ident">x</span> <span class="op">-</span> <span class="ident">x_m</span>).<span class="ident">abs</span>() <span class="op">/</span> <span class="ident">p1</span>; |
| <span class="kw">if</span> <span class="ident">v</span> <span class="op">></span> <span class="number">1.</span> { |
| <span class="kw">continue</span>; |
| } <span class="kw">else</span> { |
| <span class="ident">y</span> <span class="op">=</span> <span class="ident">f64_to_i64</span>(<span class="ident">x</span>); |
| } |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="op">!</span>(<span class="ident">u</span> <span class="op">></span> <span class="ident">p3</span>) { |
| <span class="comment">// Step 3: Region 3, left exponential tail.</span> |
| <span class="ident">y</span> <span class="op">=</span> <span class="ident">f64_to_i64</span>(<span class="ident">x_l</span> <span class="op">+</span> <span class="ident">v</span>.<span class="ident">ln</span>() <span class="op">/</span> <span class="ident">lambda_l</span>); |
| <span class="kw">if</span> <span class="ident">y</span> <span class="op"><</span> <span class="number">0</span> { |
| <span class="kw">continue</span>; |
| } <span class="kw">else</span> { |
| <span class="ident">v</span> <span class="kw-2">*</span><span class="op">=</span> (<span class="ident">u</span> <span class="op">-</span> <span class="ident">p2</span>) <span class="op">*</span> <span class="ident">lambda_l</span>; |
| } |
| } <span class="kw">else</span> { |
| <span class="comment">// Step 4: Region 4, right exponential tail.</span> |
| <span class="ident">y</span> <span class="op">=</span> <span class="ident">f64_to_i64</span>(<span class="ident">x_r</span> <span class="op">-</span> <span class="ident">v</span>.<span class="ident">ln</span>() <span class="op">/</span> <span class="ident">lambda_r</span>); |
| <span class="kw">if</span> <span class="ident">y</span> <span class="op">></span> <span class="number">0</span> <span class="op">&&</span> (<span class="ident">y</span> <span class="kw">as</span> <span class="ident">u64</span>) <span class="op">></span> <span class="self">self</span>.<span class="ident">n</span> { |
| <span class="kw">continue</span>; |
| } <span class="kw">else</span> { |
| <span class="ident">v</span> <span class="kw-2">*</span><span class="op">=</span> (<span class="ident">u</span> <span class="op">-</span> <span class="ident">p3</span>) <span class="op">*</span> <span class="ident">lambda_r</span>; |
| } |
| } |
| |
| <span class="comment">// Step 5: Acceptance/rejection comparison.</span> |
| |
| <span class="comment">// Step 5.0: Test for appropriate method of evaluating f(y).</span> |
| <span class="kw">let</span> <span class="ident">k</span> <span class="op">=</span> (<span class="ident">y</span> <span class="op">-</span> <span class="ident">m</span>).<span class="ident">abs</span>(); |
| <span class="kw">if</span> <span class="op">!</span>(<span class="ident">k</span> <span class="op">></span> <span class="ident">SQUEEZE_THRESHOLD</span> <span class="op">&&</span> (<span class="ident">k</span> <span class="kw">as</span> <span class="ident">f64</span>) <span class="op"><</span> <span class="number">0.5</span> <span class="op">*</span> <span class="ident">npq</span> <span class="op">-</span> <span class="number">1.</span>) { |
| <span class="comment">// Step 5.1: Evaluate f(y) via the recursive relationship. Start the</span> |
| <span class="comment">// search from the mode.</span> |
| <span class="kw">let</span> <span class="ident">s</span> <span class="op">=</span> <span class="ident">p</span> <span class="op">/</span> <span class="ident">q</span>; |
| <span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> <span class="ident">s</span> <span class="op">*</span> (<span class="ident">n</span> <span class="op">+</span> <span class="number">1.</span>); |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">f</span> <span class="op">=</span> <span class="number">1.0</span>; |
| <span class="kw">match</span> <span class="ident">m</span>.<span class="ident">cmp</span>(<span class="kw-2">&</span><span class="ident">y</span>) { |
| <span class="ident">Ordering::Less</span> => { |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">i</span> <span class="op">=</span> <span class="ident">m</span>; |
| <span class="kw">loop</span> { |
| <span class="ident">i</span> <span class="op">+</span><span class="op">=</span> <span class="number">1</span>; |
| <span class="ident">f</span> <span class="kw-2">*</span><span class="op">=</span> <span class="ident">a</span> <span class="op">/</span> (<span class="ident">i</span> <span class="kw">as</span> <span class="ident">f64</span>) <span class="op">-</span> <span class="ident">s</span>; |
| <span class="kw">if</span> <span class="ident">i</span> <span class="op">==</span> <span class="ident">y</span> { |
| <span class="kw">break</span>; |
| } |
| } |
| }, |
| <span class="ident">Ordering::Greater</span> => { |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">i</span> <span class="op">=</span> <span class="ident">y</span>; |
| <span class="kw">loop</span> { |
| <span class="ident">i</span> <span class="op">+</span><span class="op">=</span> <span class="number">1</span>; |
| <span class="ident">f</span> <span class="op">/</span><span class="op">=</span> <span class="ident">a</span> <span class="op">/</span> (<span class="ident">i</span> <span class="kw">as</span> <span class="ident">f64</span>) <span class="op">-</span> <span class="ident">s</span>; |
| <span class="kw">if</span> <span class="ident">i</span> <span class="op">==</span> <span class="ident">m</span> { |
| <span class="kw">break</span>; |
| } |
| } |
| }, |
| <span class="ident">Ordering::Equal</span> => {}, |
| } |
| <span class="kw">if</span> <span class="ident">v</span> <span class="op">></span> <span class="ident">f</span> { |
| <span class="kw">continue</span>; |
| } <span class="kw">else</span> { |
| <span class="kw">break</span>; |
| } |
| } |
| |
| <span class="comment">// Step 5.2: Squeezing. Check the value of ln(v) against upper and</span> |
| <span class="comment">// lower bound of ln(f(y)).</span> |
| <span class="kw">let</span> <span class="ident">k</span> <span class="op">=</span> <span class="ident">k</span> <span class="kw">as</span> <span class="ident">f64</span>; |
| <span class="kw">let</span> <span class="ident">rho</span> <span class="op">=</span> (<span class="ident">k</span> <span class="op">/</span> <span class="ident">npq</span>) <span class="op">*</span> ((<span class="ident">k</span> <span class="op">*</span> (<span class="ident">k</span> <span class="op">/</span> <span class="number">3.</span> <span class="op">+</span> <span class="number">0.625</span>) <span class="op">+</span> <span class="number">1.</span> <span class="op">/</span> <span class="number">6.</span>) <span class="op">/</span> <span class="ident">npq</span> <span class="op">+</span> <span class="number">0.5</span>); |
| <span class="kw">let</span> <span class="ident">t</span> <span class="op">=</span> <span class="op">-</span><span class="number">0.5</span> <span class="op">*</span> <span class="ident">k</span> <span class="op">*</span> <span class="ident">k</span> <span class="op">/</span> <span class="ident">npq</span>; |
| <span class="kw">let</span> <span class="ident">alpha</span> <span class="op">=</span> <span class="ident">v</span>.<span class="ident">ln</span>(); |
| <span class="kw">if</span> <span class="ident">alpha</span> <span class="op"><</span> <span class="ident">t</span> <span class="op">-</span> <span class="ident">rho</span> { |
| <span class="kw">break</span>; |
| } |
| <span class="kw">if</span> <span class="ident">alpha</span> <span class="op">></span> <span class="ident">t</span> <span class="op">+</span> <span class="ident">rho</span> { |
| <span class="kw">continue</span>; |
| } |
| |
| <span class="comment">// Step 5.3: Final acceptance/rejection test.</span> |
| <span class="kw">let</span> <span class="ident">x1</span> <span class="op">=</span> (<span class="ident">y</span> <span class="op">+</span> <span class="number">1</span>) <span class="kw">as</span> <span class="ident">f64</span>; |
| <span class="kw">let</span> <span class="ident">f1</span> <span class="op">=</span> (<span class="ident">m</span> <span class="op">+</span> <span class="number">1</span>) <span class="kw">as</span> <span class="ident">f64</span>; |
| <span class="kw">let</span> <span class="ident">z</span> <span class="op">=</span> (<span class="ident">f64_to_i64</span>(<span class="ident">n</span>) <span class="op">+</span> <span class="number">1</span> <span class="op">-</span> <span class="ident">m</span>) <span class="kw">as</span> <span class="ident">f64</span>; |
| <span class="kw">let</span> <span class="ident">w</span> <span class="op">=</span> (<span class="ident">f64_to_i64</span>(<span class="ident">n</span>) <span class="op">-</span> <span class="ident">y</span> <span class="op">+</span> <span class="number">1</span>) <span class="kw">as</span> <span class="ident">f64</span>; |
| |
| <span class="kw">fn</span> <span class="ident">stirling</span>(<span class="ident">a</span>: <span class="ident">f64</span>) -> <span class="ident">f64</span> { |
| <span class="kw">let</span> <span class="ident">a2</span> <span class="op">=</span> <span class="ident">a</span> <span class="op">*</span> <span class="ident">a</span>; |
| (<span class="number">13860.</span> <span class="op">-</span> (<span class="number">462.</span> <span class="op">-</span> (<span class="number">132.</span> <span class="op">-</span> (<span class="number">99.</span> <span class="op">-</span> <span class="number">140.</span> <span class="op">/</span> <span class="ident">a2</span>) <span class="op">/</span> <span class="ident">a2</span>) <span class="op">/</span> <span class="ident">a2</span>) <span class="op">/</span> <span class="ident">a2</span>) <span class="op">/</span> <span class="ident">a</span> <span class="op">/</span> <span class="number">166320.</span> |
| } |
| |
| <span class="kw">if</span> <span class="ident">alpha</span> |
| <span class="op">></span> <span class="ident">x_m</span> <span class="op">*</span> (<span class="ident">f1</span> <span class="op">/</span> <span class="ident">x1</span>).<span class="ident">ln</span>() |
| <span class="op">+</span> (<span class="ident">n</span> <span class="op">-</span> (<span class="ident">m</span> <span class="kw">as</span> <span class="ident">f64</span>) <span class="op">+</span> <span class="number">0.5</span>) <span class="op">*</span> (<span class="ident">z</span> <span class="op">/</span> <span class="ident">w</span>).<span class="ident">ln</span>() |
| <span class="op">+</span> ((<span class="ident">y</span> <span class="op">-</span> <span class="ident">m</span>) <span class="kw">as</span> <span class="ident">f64</span>) <span class="op">*</span> (<span class="ident">w</span> <span class="op">*</span> <span class="ident">p</span> <span class="op">/</span> (<span class="ident">x1</span> <span class="op">*</span> <span class="ident">q</span>)).<span class="ident">ln</span>() |
| <span class="comment">// We use the signs from the GSL implementation, which are</span> |
| <span class="comment">// different than the ones in the reference. According to</span> |
| <span class="comment">// the GSL authors, the new signs were verified to be</span> |
| <span class="comment">// correct by one of the original designers of the</span> |
| <span class="comment">// algorithm.</span> |
| <span class="op">+</span> <span class="ident">stirling</span>(<span class="ident">f1</span>) |
| <span class="op">+</span> <span class="ident">stirling</span>(<span class="ident">z</span>) |
| <span class="op">-</span> <span class="ident">stirling</span>(<span class="ident">x1</span>) |
| <span class="op">-</span> <span class="ident">stirling</span>(<span class="ident">w</span>) |
| { |
| <span class="kw">continue</span>; |
| } |
| |
| <span class="kw">break</span>; |
| } |
| <span class="macro">assert!</span>(<span class="ident">y</span> <span class="op">></span><span class="op">=</span> <span class="number">0</span>); |
| <span class="ident">result</span> <span class="op">=</span> <span class="ident">y</span> <span class="kw">as</span> <span class="ident">u64</span>; |
| } |
| |
| <span class="comment">// Invert the result for p < 0.5.</span> |
| <span class="kw">if</span> <span class="ident">p</span> <span class="op">!</span><span class="op">=</span> <span class="self">self</span>.<span class="ident">p</span> { |
| <span class="self">self</span>.<span class="ident">n</span> <span class="op">-</span> <span class="ident">result</span> |
| } <span class="kw">else</span> { |
| <span class="ident">result</span> |
| } |
| } |
| } |
| |
| <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span> |
| <span class="kw">mod</span> <span class="ident">test</span> { |
| <span class="kw">use</span> <span class="ident"><span class="kw">super</span>::Binomial</span>; |
| <span class="kw">use</span> <span class="ident"><span class="kw">crate</span>::Distribution</span>; |
| <span class="kw">use</span> <span class="ident">rand::Rng</span>; |
| |
| <span class="kw">fn</span> <span class="ident">test_binomial_mean_and_variance</span><span class="op"><</span><span class="ident">R</span>: <span class="ident">Rng</span><span class="op">></span>(<span class="ident">n</span>: <span class="ident">u64</span>, <span class="ident">p</span>: <span class="ident">f64</span>, <span class="ident">rng</span>: <span class="kw-2">&mut</span> <span class="ident">R</span>) { |
| <span class="kw">let</span> <span class="ident">binomial</span> <span class="op">=</span> <span class="ident">Binomial::new</span>(<span class="ident">n</span>, <span class="ident">p</span>).<span class="ident">unwrap</span>(); |
| |
| <span class="kw">let</span> <span class="ident">expected_mean</span> <span class="op">=</span> <span class="ident">n</span> <span class="kw">as</span> <span class="ident">f64</span> <span class="op">*</span> <span class="ident">p</span>; |
| <span class="kw">let</span> <span class="ident">expected_variance</span> <span class="op">=</span> <span class="ident">n</span> <span class="kw">as</span> <span class="ident">f64</span> <span class="op">*</span> <span class="ident">p</span> <span class="op">*</span> (<span class="number">1.0</span> <span class="op">-</span> <span class="ident">p</span>); |
| |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">results</span> <span class="op">=</span> [<span class="number">0.0</span>; <span class="number">1000</span>]; |
| <span class="kw">for</span> <span class="ident">i</span> <span class="kw">in</span> <span class="ident">results</span>.<span class="ident">iter_mut</span>() { |
| <span class="kw-2">*</span><span class="ident">i</span> <span class="op">=</span> <span class="ident">binomial</span>.<span class="ident">sample</span>(<span class="ident">rng</span>) <span class="kw">as</span> <span class="ident">f64</span>; |
| } |
| |
| <span class="kw">let</span> <span class="ident">mean</span> <span class="op">=</span> <span class="ident">results</span>.<span class="ident">iter</span>().<span class="ident">sum</span>::<span class="op"><</span><span class="ident">f64</span><span class="op">></span>() <span class="op">/</span> <span class="ident">results</span>.<span class="ident">len</span>() <span class="kw">as</span> <span class="ident">f64</span>; |
| <span class="macro">assert!</span>((<span class="ident">mean</span> <span class="kw">as</span> <span class="ident">f64</span> <span class="op">-</span> <span class="ident">expected_mean</span>).<span class="ident">abs</span>() <span class="op"><</span> <span class="ident">expected_mean</span> <span class="op">/</span> <span class="number">50.0</span>); |
| |
| <span class="kw">let</span> <span class="ident">variance</span> <span class="op">=</span> |
| <span class="ident">results</span>.<span class="ident">iter</span>().<span class="ident">map</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> (<span class="ident">x</span> <span class="op">-</span> <span class="ident">mean</span>) <span class="op">*</span> (<span class="ident">x</span> <span class="op">-</span> <span class="ident">mean</span>)).<span class="ident">sum</span>::<span class="op"><</span><span class="ident">f64</span><span class="op">></span>() <span class="op">/</span> <span class="ident">results</span>.<span class="ident">len</span>() <span class="kw">as</span> <span class="ident">f64</span>; |
| <span class="macro">assert!</span>((<span class="ident">variance</span> <span class="op">-</span> <span class="ident">expected_variance</span>).<span class="ident">abs</span>() <span class="op"><</span> <span class="ident">expected_variance</span> <span class="op">/</span> <span class="number">10.0</span>); |
| } |
| |
| <span class="attribute">#[<span class="ident">test</span>]</span> |
| <span class="kw">fn</span> <span class="ident">test_binomial</span>() { |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">rng</span> <span class="op">=</span> <span class="ident"><span class="kw">crate</span>::test::rng</span>(<span class="number">351</span>); |
| <span class="ident">test_binomial_mean_and_variance</span>(<span class="number">150</span>, <span class="number">0.1</span>, <span class="kw-2">&mut</span> <span class="ident">rng</span>); |
| <span class="ident">test_binomial_mean_and_variance</span>(<span class="number">70</span>, <span class="number">0.6</span>, <span class="kw-2">&mut</span> <span class="ident">rng</span>); |
| <span class="ident">test_binomial_mean_and_variance</span>(<span class="number">40</span>, <span class="number">0.5</span>, <span class="kw-2">&mut</span> <span class="ident">rng</span>); |
| <span class="ident">test_binomial_mean_and_variance</span>(<span class="number">20</span>, <span class="number">0.7</span>, <span class="kw-2">&mut</span> <span class="ident">rng</span>); |
| <span class="ident">test_binomial_mean_and_variance</span>(<span class="number">20</span>, <span class="number">0.5</span>, <span class="kw-2">&mut</span> <span class="ident">rng</span>); |
| } |
| |
| <span class="attribute">#[<span class="ident">test</span>]</span> |
| <span class="kw">fn</span> <span class="ident">test_binomial_end_points</span>() { |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">rng</span> <span class="op">=</span> <span class="ident"><span class="kw">crate</span>::test::rng</span>(<span class="number">352</span>); |
| <span class="macro">assert_eq!</span>(<span class="ident">rng</span>.<span class="ident">sample</span>(<span class="ident">Binomial::new</span>(<span class="number">20</span>, <span class="number">0.0</span>).<span class="ident">unwrap</span>()), <span class="number">0</span>); |
| <span class="macro">assert_eq!</span>(<span class="ident">rng</span>.<span class="ident">sample</span>(<span class="ident">Binomial::new</span>(<span class="number">20</span>, <span class="number">1.0</span>).<span class="ident">unwrap</span>()), <span class="number">20</span>); |
| } |
| |
| <span class="attribute">#[<span class="ident">test</span>]</span> |
| <span class="attribute">#[<span class="ident">should_panic</span>]</span> |
| <span class="kw">fn</span> <span class="ident">test_binomial_invalid_lambda_neg</span>() { |
| <span class="ident">Binomial::new</span>(<span class="number">20</span>, <span class="op">-</span><span class="number">10.0</span>).<span class="ident">unwrap</span>(); |
| } |
| } |
| </code></pre></div> |
| </section><section id="search" class="content hidden"></section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="rand_distr" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.60.0-nightly (1bd4fdc94 2022-01-12)" ></div> |
| </body></html> |
