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| </pre><pre class="rust"><code><span class="doccomment">//! The geometric distribution.</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">use</span> <span class="ident">core::fmt</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 geometric distribution `Geometric(p)` bounded to `[0, u64::MAX]`.</span> |
| <span class="doccomment">/// </span> |
| <span class="doccomment">/// This is the probability distribution of the number of failures before the</span> |
| <span class="doccomment">/// first success in a series of Bernoulli trials. It has the density function</span> |
| <span class="doccomment">/// `f(k) = (1 - p)^k p` for `k >= 0`, where `p` is the probability of success</span> |
| <span class="doccomment">/// on each trial.</span> |
| <span class="doccomment">/// </span> |
| <span class="doccomment">/// This is the discrete analogue of the [exponential distribution](crate::Exp).</span> |
| <span class="doccomment">/// </span> |
| <span class="doccomment">/// Note that [`StandardGeometric`](crate::StandardGeometric) is an optimised</span> |
| <span class="doccomment">/// implementation for `p = 0.5`.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// # Example</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// ```</span> |
| <span class="doccomment">/// use rand_distr::{Geometric, Distribution};</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// let geo = Geometric::new(0.25).unwrap();</span> |
| <span class="doccomment">/// let v = geo.sample(&mut rand::thread_rng());</span> |
| <span class="doccomment">/// println!("{} is from a Geometric(0.25) distribution", v);</span> |
| <span class="doccomment">/// ```</span> |
| <span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Copy</span>, <span class="ident">Clone</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">Geometric</span> |
| { |
| <span class="ident">p</span>: <span class="ident">f64</span>, |
| <span class="ident">pi</span>: <span class="ident">f64</span>, |
| <span class="ident">k</span>: <span class="ident">u64</span> |
| } |
| |
| <span class="doccomment">/// Error type returned from `Geometric::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 || p > 1` or `nan`</span> |
| <span class="ident">InvalidProbability</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::InvalidProbability</span> => <span class="string">"p is NaN or outside the interval [0, 1] in geometric 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">Geometric</span> { |
| <span class="doccomment">/// Construct a new `Geometric` with the given shape parameter `p`</span> |
| <span class="doccomment">/// (probability of success on each trial).</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new</span>(<span class="ident">p</span>: <span class="ident">f64</span>) -> <span class="prelude-ty">Result</span><span class="op"><</span><span class="self">Self</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="ident">is_finite</span>() <span class="op">|</span><span class="op">|</span> <span class="ident">p</span> <span class="op"><</span> <span class="number">0.0</span> <span class="op">|</span><span class="op">|</span> <span class="ident">p</span> <span class="op">></span> <span class="number">1.0</span> { |
| <span class="prelude-val">Err</span>(<span class="ident">Error::InvalidProbability</span>) |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="ident">p</span> <span class="op">==</span> <span class="number">0.0</span> <span class="op">|</span><span class="op">|</span> <span class="ident">p</span> <span class="op">></span><span class="op">=</span> <span class="number">2.0</span> <span class="op">/</span> <span class="number">3.0</span> { |
| <span class="prelude-val">Ok</span>(<span class="ident">Geometric</span> { <span class="ident">p</span>, <span class="ident">pi</span>: <span class="ident">p</span>, <span class="ident">k</span>: <span class="number">0</span> }) |
| } <span class="kw">else</span> { |
| <span class="kw">let</span> (<span class="ident">pi</span>, <span class="ident">k</span>) <span class="op">=</span> { |
| <span class="comment">// choose smallest k such that pi = (1 - p)^(2^k) <= 0.5</span> |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">k</span> <span class="op">=</span> <span class="number">1</span>; |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">pi</span> <span class="op">=</span> (<span class="number">1.0</span> <span class="op">-</span> <span class="ident">p</span>).<span class="ident">powi</span>(<span class="number">2</span>); |
| <span class="kw">while</span> <span class="ident">pi</span> <span class="op">></span> <span class="number">0.5</span> { |
| <span class="ident">k</span> <span class="op">+</span><span class="op">=</span> <span class="number">1</span>; |
| <span class="ident">pi</span> <span class="op">=</span> <span class="ident">pi</span> <span class="op">*</span> <span class="ident">pi</span>; |
| } |
| (<span class="ident">pi</span>, <span class="ident">k</span>) |
| }; |
| |
| <span class="prelude-val">Ok</span>(<span class="ident">Geometric</span> { <span class="ident">p</span>, <span class="ident">pi</span>, <span class="ident">k</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">Geometric</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="kw">if</span> <span class="self">self</span>.<span class="ident">p</span> <span class="op">></span><span class="op">=</span> <span class="number">2.0</span> <span class="op">/</span> <span class="number">3.0</span> { |
| <span class="comment">// use the trivial algorithm:</span> |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">failures</span> <span class="op">=</span> <span class="number">0</span>; |
| <span class="kw">loop</span> { |
| <span class="kw">let</span> <span class="ident">u</span> <span class="op">=</span> <span class="ident">rng</span>.<span class="ident">gen</span>::<span class="op"><</span><span class="ident">f64</span><span class="op">></span>(); |
| <span class="kw">if</span> <span class="ident">u</span> <span class="op"><</span><span class="op">=</span> <span class="self">self</span>.<span class="ident">p</span> { <span class="kw">break</span>; } |
| <span class="ident">failures</span> <span class="op">+</span><span class="op">=</span> <span class="number">1</span>; |
| } |
| <span class="kw">return</span> <span class="ident">failures</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="ident">core::u64::MAX</span>; } |
| |
| <span class="kw">let</span> <span class="ident">Geometric</span> { <span class="ident">p</span>, <span class="ident">pi</span>, <span class="ident">k</span> } <span class="op">=</span> <span class="kw-2">*</span><span class="self">self</span>; |
| |
| <span class="comment">// Based on the algorithm presented in section 3 of</span> |
| <span class="comment">// Karl Bringmann and Tobias Friedrich (July 2013) - Exact and Efficient</span> |
| <span class="comment">// Generation of Geometric Random Variates and Random Graphs, published</span> |
| <span class="comment">// in International Colloquium on Automata, Languages and Programming</span> |
| <span class="comment">// (pp.267-278)</span> |
| <span class="comment">// https://people.mpi-inf.mpg.de/~kbringma/paper/2013ICALP-1.pdf</span> |
| |
| <span class="comment">// Use the trivial algorithm to sample D from Geo(pi) = Geo(p) / 2^k:</span> |
| <span class="kw">let</span> <span class="ident">d</span> <span class="op">=</span> { |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">failures</span> <span class="op">=</span> <span class="number">0</span>; |
| <span class="kw">while</span> <span class="ident">rng</span>.<span class="ident">gen</span>::<span class="op"><</span><span class="ident">f64</span><span class="op">></span>() <span class="op"><</span> <span class="ident">pi</span> { |
| <span class="ident">failures</span> <span class="op">+</span><span class="op">=</span> <span class="number">1</span>; |
| } |
| <span class="ident">failures</span> |
| }; |
| |
| <span class="comment">// Use rejection sampling for the remainder M from Geo(p) % 2^k:</span> |
| <span class="comment">// choose M uniformly from [0, 2^k), but reject with probability (1 - p)^M</span> |
| <span class="comment">// NOTE: The paper suggests using bitwise sampling here, which is </span> |
| <span class="comment">// currently unsupported, but should improve performance by requiring</span> |
| <span class="comment">// fewer iterations on average. ~ October 28, 2020</span> |
| <span class="kw">let</span> <span class="ident">m</span> <span class="op">=</span> <span class="kw">loop</span> { |
| <span class="kw">let</span> <span class="ident">m</span> <span class="op">=</span> <span class="ident">rng</span>.<span class="ident">gen</span>::<span class="op"><</span><span class="ident">u64</span><span class="op">></span>() <span class="op">&</span> ((<span class="number">1</span> <span class="op"><</span><span class="op"><</span> <span class="ident">k</span>) <span class="op">-</span> <span class="number">1</span>); |
| <span class="kw">let</span> <span class="ident">p_reject</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">m</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="number">1.0</span> <span class="op">-</span> <span class="ident">p</span>).<span class="ident">powi</span>(<span class="ident">m</span> <span class="kw">as</span> <span class="ident">i32</span>) |
| } <span class="kw">else</span> { |
| (<span class="number">1.0</span> <span class="op">-</span> <span class="ident">p</span>).<span class="ident">powf</span>(<span class="ident">m</span> <span class="kw">as</span> <span class="ident">f64</span>) |
| }; |
| |
| <span class="kw">let</span> <span class="ident">u</span> <span class="op">=</span> <span class="ident">rng</span>.<span class="ident">gen</span>::<span class="op"><</span><span class="ident">f64</span><span class="op">></span>(); |
| <span class="kw">if</span> <span class="ident">u</span> <span class="op"><</span> <span class="ident">p_reject</span> { |
| <span class="kw">break</span> <span class="ident">m</span>; |
| } |
| }; |
| |
| (<span class="ident">d</span> <span class="op"><</span><span class="op"><</span> <span class="ident">k</span>) <span class="op">+</span> <span class="ident">m</span> |
| } |
| } |
| |
| <span class="doccomment">/// Samples integers according to the geometric distribution with success</span> |
| <span class="doccomment">/// probability `p = 0.5`. This is equivalent to `Geometeric::new(0.5)`,</span> |
| <span class="doccomment">/// but faster.</span> |
| <span class="doccomment">/// </span> |
| <span class="doccomment">/// See [`Geometric`](crate::Geometric) for the general geometric distribution.</span> |
| <span class="doccomment">/// </span> |
| <span class="doccomment">/// Implemented via iterated [Rng::gen::<u64>().leading_zeros()].</span> |
| <span class="doccomment">/// </span> |
| <span class="doccomment">/// # Example</span> |
| <span class="doccomment">/// ```</span> |
| <span class="doccomment">/// use rand::prelude::*;</span> |
| <span class="doccomment">/// use rand_distr::StandardGeometric;</span> |
| <span class="doccomment">/// </span> |
| <span class="doccomment">/// let v = StandardGeometric.sample(&mut thread_rng());</span> |
| <span class="doccomment">/// println!("{} is from a Geometric(0.5) distribution", v);</span> |
| <span class="doccomment">/// ```</span> |
| <span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Copy</span>, <span class="ident">Clone</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">StandardGeometric</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">StandardGeometric</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="kw">let</span> <span class="kw-2">mut</span> <span class="ident">result</span> <span class="op">=</span> <span class="number">0</span>; |
| <span class="kw">loop</span> { |
| <span class="kw">let</span> <span class="ident">x</span> <span class="op">=</span> <span class="ident">rng</span>.<span class="ident">gen</span>::<span class="op"><</span><span class="ident">u64</span><span class="op">></span>().<span class="ident">leading_zeros</span>() <span class="kw">as</span> <span class="ident">u64</span>; |
| <span class="ident">result</span> <span class="op">+</span><span class="op">=</span> <span class="ident">x</span>; |
| <span class="kw">if</span> <span class="ident">x</span> <span class="op"><</span> <span class="number">64</span> { <span class="kw">break</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="kw">super</span>::<span class="kw-2">*</span>; |
| |
| <span class="attribute">#[<span class="ident">test</span>]</span> |
| <span class="kw">fn</span> <span class="ident">test_geo_invalid_p</span>() { |
| <span class="macro">assert!</span>(<span class="ident">Geometric::new</span>(<span class="ident">core::f64::NAN</span>).<span class="ident">is_err</span>()); |
| <span class="macro">assert!</span>(<span class="ident">Geometric::new</span>(<span class="ident">core::f64::INFINITY</span>).<span class="ident">is_err</span>()); |
| <span class="macro">assert!</span>(<span class="ident">Geometric::new</span>(<span class="ident">core::f64::NEG_INFINITY</span>).<span class="ident">is_err</span>()); |
| |
| <span class="macro">assert!</span>(<span class="ident">Geometric::new</span>(<span class="op">-</span><span class="number">0.5</span>).<span class="ident">is_err</span>()); |
| <span class="macro">assert!</span>(<span class="ident">Geometric::new</span>(<span class="number">0.0</span>).<span class="ident">is_ok</span>()); |
| <span class="macro">assert!</span>(<span class="ident">Geometric::new</span>(<span class="number">1.0</span>).<span class="ident">is_ok</span>()); |
| <span class="macro">assert!</span>(<span class="ident">Geometric::new</span>(<span class="number">2.0</span>).<span class="ident">is_err</span>()); |
| } |
| |
| <span class="kw">fn</span> <span class="ident">test_geo_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">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">distr</span> <span class="op">=</span> <span class="ident">Geometric::new</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="number">1.0</span> <span class="op">-</span> <span class="ident">p</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="number">1.0</span> <span class="op">-</span> <span class="ident">p</span>) <span class="op">/</span> (<span class="ident">p</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">10000</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">distr</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">40.0</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_geometric</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">12345</span>); |
| |
| <span class="ident">test_geo_mean_and_variance</span>(<span class="number">0.10</span>, <span class="kw-2">&mut</span> <span class="ident">rng</span>); |
| <span class="ident">test_geo_mean_and_variance</span>(<span class="number">0.25</span>, <span class="kw-2">&mut</span> <span class="ident">rng</span>); |
| <span class="ident">test_geo_mean_and_variance</span>(<span class="number">0.50</span>, <span class="kw-2">&mut</span> <span class="ident">rng</span>); |
| <span class="ident">test_geo_mean_and_variance</span>(<span class="number">0.75</span>, <span class="kw-2">&mut</span> <span class="ident">rng</span>); |
| <span class="ident">test_geo_mean_and_variance</span>(<span class="number">0.90</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_standard_geometric</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">654321</span>); |
| |
| <span class="kw">let</span> <span class="ident">distr</span> <span class="op">=</span> <span class="ident">StandardGeometric</span>; |
| <span class="kw">let</span> <span class="ident">expected_mean</span> <span class="op">=</span> <span class="number">1.0</span>; |
| <span class="kw">let</span> <span class="ident">expected_variance</span> <span class="op">=</span> <span class="number">2.0</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">distr</span>.<span class="ident">sample</span>(<span class="kw-2">&mut</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>); |
| } |
| } |
| </code></pre></div> |
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