1 files changed, 59 insertions, 0 deletions
diff --git a/rand/rand_distr/tests/uniformity.rs b/rand/rand_distr/tests/uniformity.rs
new file mode 100644
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+++ b/rand/rand_distr/tests/uniformity.rs
@@ -0,0 +1,59 @@
+// 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.
+
+use average::Histogram;
+use rand::prelude::*;
+
+const N_BINS: usize = 100;
+const N_SAMPLES: u32 = 1_000_000;
+const TOL: f64 = 1e-3;
+average::define_histogram!(hist, 100);
+use hist::Histogram as Histogram100;
+
+#[test]
+fn unit_sphere() {
+    const N_DIM: usize = 3;
+    let h = Histogram100::with_const_width(-1., 1.);
+    let mut histograms = [h.clone(), h.clone(), h];
+    let dist = rand_distr::UnitSphere;
+    let mut rng = rand_pcg::Pcg32::from_entropy();
+    for _ in 0..N_SAMPLES {
+        let v: [f64; 3] = dist.sample(&mut rng);
+        for i in 0..N_DIM {
+            histograms[i].add(v[i]).map_err(
+                |e| { println!("v: {}", v[i]); e }
+            ).unwrap();
+        }
+    }
+    for h in &histograms {
+        let sum: u64 = h.bins().iter().sum();
+        println!("{:?}", h);
+        for &b in h.bins() {
+            let p = (b as f64) / (sum as f64);
+            assert!((p - 1.0 / (N_BINS as f64)).abs() < TOL, "{}", p);
+        }
+    }
+}
+
+#[test]
+fn unit_circle() {
+    use std::f64::consts::PI;
+    let mut h = Histogram100::with_const_width(-PI, PI);
+    let dist = rand_distr::UnitCircle;
+    let mut rng = rand_pcg::Pcg32::from_entropy();
+    for _ in 0..N_SAMPLES {
+        let v: [f64; 2] = dist.sample(&mut rng);
+        h.add(v[0].atan2(v[1])).unwrap();
+    }
+    let sum: u64 = h.bins().iter().sum();
+    println!("{:?}", h);
+    for &b in h.bins() {
+        let p = (b as f64) / (sum as f64);
+        assert!((p - 1.0 / (N_BINS as f64)).abs() < TOL, "{}", p);
+    }
+}