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< h1 class = 'fqn' > < span class = 'in-band' > Struct < a href = '../../index.html' > rand< / a > ::< wbr > < a href = '../index.html' > distributions< / a > ::< wbr > < a href = 'index.html' > gamma< / a > ::< wbr > < a class = 'struct' href = '' > Gamma< / a > < / span > < span class = 'out-of-band' > < span id = 'render-detail' >
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< / span > < a id = 'src-212' class = 'srclink' href = '../../../src/rand/distributions/gamma.rs.html#53-55' title = 'goto source code' > [src]< / a > < / span > < / h1 >
< pre class = 'rust struct' > pub struct Gamma {
// some fields omitted
}< / pre > < div class = 'docblock' > < p > The Gamma distribution < code > Gamma(shape, scale)< / code > distribution.< / p >
< p > The density function of this distribution is< / p >
< pre > < code class = "language-text" > f(x) = x^(k - 1) * exp(-x / θ) / (Γ(k) * θ^k)
< / code > < / pre >
< p > where < code > Γ< / code > is the Gamma function, < code > k< / code > is the shape and < code > θ< / code > is the
scale and both < code > k< / code > and < code > θ< / code > are strictly positive.< / p >
< p > The algorithm used is that described by Marsaglia & Tsang 2000[1],
falling back to directly sampling from an Exponential for < code > shape == 1< / code > , and using the boosting technique described in [1] for
< code > shape < 1< / code > .< / p >
< h1 id = 'example' class = 'section-header' > < a href = '#example' > Example< / a > < / h1 >
< pre class = 'rust rust-example-rendered' >
< span class = 'kw' > use< / span > < span class = 'ident' > rand< / span > ::< span class = 'ident' > distributions< / span > ::{< span class = 'ident' > IndependentSample< / span > , < span class = 'ident' > Gamma< / span > };
< span class = 'kw' > let< / span > < span class = 'ident' > gamma< / span > < span class = 'op' > =< / span > < span class = 'ident' > Gamma< / span > ::< span class = 'ident' > new< / span > (< span class = 'number' > 2.0< / span > , < span class = 'number' > 5.0< / span > );
< span class = 'kw' > let< / span > < span class = 'ident' > v< / span > < span class = 'op' > =< / span > < span class = 'ident' > gamma< / span > .< span class = 'ident' > ind_sample< / span > (< span class = 'kw-2' > & < / span > < span class = 'kw-2' > mut< / span > < span class = 'ident' > rand< / span > ::< span class = 'ident' > thread_rng< / span > ());
< span class = 'macro' > println< / span > < span class = 'macro' > !< / span > (< span class = 'string' > " {} is from a Gamma(2, 5) distribution" < / span > , < span class = 'ident' > v< / span > );< / pre >
< p > [1]: George Marsaglia and Wai Wan Tsang. 2000. " A Simple Method
for Generating Gamma Variables" < em > ACM Trans. Math. Softw.< / em > 26, 3
(September 2000),
363-372. DOI:< a href = "http://doi.acm.org/10.1145/358407.358414" > 10.1145/358407.358414< / a > < / p >
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< / div > < h2 id = 'methods' > Methods< / h2 > < h3 class = 'impl' > < span class = 'in-band' > < code > impl < a class = 'struct' href = '../../../rand/distributions/gamma/struct.Gamma.html' title = 'rand::distributions::gamma::Gamma' > Gamma< / a > < / code > < / span > < span class = 'out-of-band' > < div class = 'ghost' > < / div > < a id = 'src-253' class = 'srclink' href = '../../../src/rand/distributions/gamma.rs.html#95-111' title = 'goto source code' > [src]< / a > < / span > < / h3 >
< div class = 'impl-items' > < h4 id = 'method.new' class = 'method' > < code > fn < a href = '#method.new' class = 'fnname' > new< / a > (shape: < a class = 'primitive' href = 'https://doc.rust-lang.org/nightly/std/primitive.f64.html' > f64< / a > , scale: < a class = 'primitive' href = 'https://doc.rust-lang.org/nightly/std/primitive.f64.html' > f64< / a > ) -> < a class = 'struct' href = '../../../rand/distributions/gamma/struct.Gamma.html' title = 'rand::distributions::gamma::Gamma' > Gamma< / a > < / code > < / h4 >
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< div class = 'docblock' > < p > Construct an object representing the < code > Gamma(shape, scale)< / code >
distribution.< / p >
< p > Panics if < code > shape < = 0< / code > or < code > scale < = 0< / code > .< / p >
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< / div > < / div > < h2 id = 'implementations' > Trait Implementations< / h2 > < h3 class = 'impl' > < span class = 'in-band' > < code > impl < a class = 'trait' href = '../../../rand/distributions/trait.Sample.html' title = 'rand::distributions::Sample' > Sample< / a > < < a class = 'primitive' href = 'https://doc.rust-lang.org/nightly/std/primitive.f64.html' > f64< / a > > for < a class = 'struct' href = '../../../rand/distributions/gamma/struct.Gamma.html' title = 'rand::distributions::gamma::Gamma' > Gamma< / a > < / code > < / span > < span class = 'out-of-band' > < div class = 'ghost' > < / div > < a id = 'src-269' class = 'srclink' href = '../../../src/rand/distributions/gamma.rs.html#133-135' title = 'goto source code' > [src]< / a > < / span > < / h3 >
< div class = 'impl-items' > < h4 id = 'method.sample' class = 'method' > < code > fn < a href = '../../../rand/distributions/trait.Sample.html#tymethod.sample' class = 'fnname' > sample< / a > < R: < a class = 'trait' href = '../../../rand/trait.Rng.html' title = 'rand::Rng' > Rng< / a > > (& mut self, rng: & mut R) -> < a class = 'primitive' href = 'https://doc.rust-lang.org/nightly/std/primitive.f64.html' > f64< / a > < / code > < / h4 >
< / div > < h3 class = 'impl' > < span class = 'in-band' > < code > impl < a class = 'trait' href = '../../../rand/distributions/trait.IndependentSample.html' title = 'rand::distributions::IndependentSample' > IndependentSample< / a > < < a class = 'primitive' href = 'https://doc.rust-lang.org/nightly/std/primitive.f64.html' > f64< / a > > for < a class = 'struct' href = '../../../rand/distributions/gamma/struct.Gamma.html' title = 'rand::distributions::gamma::Gamma' > Gamma< / a > < / code > < / span > < span class = 'out-of-band' > < div class = 'ghost' > < / div > < a id = 'src-284' class = 'srclink' href = '../../../src/rand/distributions/gamma.rs.html#143-151' title = 'goto source code' > [src]< / a > < / span > < / h3 >
< div class = 'impl-items' > < h4 id = 'method.ind_sample' class = 'method' > < code > fn < a href = '../../../rand/distributions/trait.IndependentSample.html#tymethod.ind_sample' class = 'fnname' > ind_sample< / a > < R: < a class = 'trait' href = '../../../rand/trait.Rng.html' title = 'rand::Rng' > Rng< / a > > (& self, rng: & mut R) -> < a class = 'primitive' href = 'https://doc.rust-lang.org/nightly/std/primitive.f64.html' > f64< / a > < / code > < / h4 >
< / div > < h3 id = 'derived_implementations' > Derived Implementations < / h3 > < h3 class = 'impl' > < span class = 'in-band' > < code > impl < a class = 'trait' href = 'https://doc.rust-lang.org/nightly/core/marker/trait.Copy.html' title = 'core::marker::Copy' > Copy< / a > for < a class = 'struct' href = '../../../rand/distributions/gamma/struct.Gamma.html' title = 'rand::distributions::gamma::Gamma' > Gamma< / a > < / code > < / span > < span class = 'out-of-band' > < div class = 'ghost' > < / div > < a id = 'src-214' class = 'srclink' href = '../../../src/rand/distributions/gamma.rs.html#52' title = 'goto source code' > [src]< / a > < / span > < / h3 >
< div class = 'impl-items' > < / div > < h3 class = 'impl' > < span class = 'in-band' > < code > impl < a class = 'trait' href = 'https://doc.rust-lang.org/nightly/core/clone/trait.Clone.html' title = 'core::clone::Clone' > Clone< / a > for < a class = 'struct' href = '../../../rand/distributions/gamma/struct.Gamma.html' title = 'rand::distributions::gamma::Gamma' > Gamma< / a > < / code > < / span > < span class = 'out-of-band' > < div class = 'ghost' > < / div > < a id = 'src-215' class = 'srclink' href = '../../../src/rand/distributions/gamma.rs.html#52' title = 'goto source code' > [src]< / a > < / span > < / h3 >
< div class = 'impl-items' > < h4 id = 'method.clone' class = 'method' > < code > fn < a href = 'https://doc.rust-lang.org/nightly/core/clone/trait.Clone.html#tymethod.clone' class = 'fnname' > clone< / a > (& self) -> < a class = 'struct' href = '../../../rand/distributions/gamma/struct.Gamma.html' title = 'rand::distributions::gamma::Gamma' > Gamma< / a > < / code > < / h4 >
< h4 id = 'method.clone_from' class = 'method' > < code > fn < a href = 'https://doc.rust-lang.org/nightly/core/clone/trait.Clone.html#method.clone_from' class = 'fnname' > clone_from< / a > (& mut self, source: & Self)< / code > < div class = "since" > 1.0.0< / div > < / h4 >
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