Merge tag 'debian/1.52.1+dfsg1-1_exp2' into proxmox/buster

[rustc.git] / vendor / rand-0.7.3 / src / distributions / pareto.rs

diff --git a/vendor/rand-0.7.3/src/distributions/pareto.rs b/vendor/rand-0.7.3/src/distributions/pareto.rs
new file mode 100644 (file)
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+// Copyright 2018 Developers of the Rand project.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! The Pareto distribution.
+#![allow(deprecated)]
+
+use crate::distributions::{Distribution, OpenClosed01};
+use crate::Rng;
+
+/// Samples floating-point numbers according to the Pareto distribution
+#[deprecated(since = "0.7.0", note = "moved to rand_distr crate")]
+#[derive(Clone, Copy, Debug)]
+pub struct Pareto {
+    scale: f64,
+    inv_neg_shape: f64,
+}
+
+impl Pareto {
+    /// Construct a new Pareto distribution with given `scale` and `shape`.
+    ///
+    /// In the literature, `scale` is commonly written as x<sub>m</sub> or k and
+    /// `shape` is often written as α.
+    ///
+    /// # Panics
+    ///
+    /// `scale` and `shape` have to be non-zero and positive.
+    pub fn new(scale: f64, shape: f64) -> Pareto {
+        assert!((scale > 0.) & (shape > 0.));
+        Pareto {
+            scale,
+            inv_neg_shape: -1.0 / shape,
+        }
+    }
+}
+
+impl Distribution<f64> for Pareto {
+    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> f64 {
+        let u: f64 = rng.sample(OpenClosed01);
+        self.scale * u.powf(self.inv_neg_shape)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Pareto;
+    use crate::distributions::Distribution;
+
+    #[test]
+    #[should_panic]
+    fn invalid() {
+        Pareto::new(0., 0.);
+    }
+
+    #[test]
+    fn sample() {
+        let scale = 1.0;
+        let shape = 2.0;
+        let d = Pareto::new(scale, shape);
+        let mut rng = crate::test::rng(1);
+        for _ in 0..1000 {
+            let r = d.sample(&mut rng);
+            assert!(r >= scale);
+        }
+    }
+}