From 378cad782703c87821c3376b7cf776c82d1406fe Mon Sep 17 00:00:00 2001
From: Diggory Hardy <git@dhardy.name>
Date: Sun, 13 Dec 2020 10:24:54 +0000
Subject: [PATCH] More precision lowering

---
 rand_distr/tests/value_stability.rs | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/rand_distr/tests/value_stability.rs b/rand_distr/tests/value_stability.rs
index 525663effc..8db9b3b46e 100644
--- a/rand_distr/tests/value_stability.rs
+++ b/rand_distr/tests/value_stability.rs
@@ -6,7 +6,9 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use core::{fmt::Debug, cmp::PartialEq};
+use core::fmt::{Debug, Display};
+use core::cmp::PartialEq;
+use num_traits::Float;
 use rand::Rng;
 use rand_distr::*;
 
@@ -26,6 +28,16 @@ fn test_samples<F: Debug + Copy + PartialEq, D: Distribution<F>>(
     }
 }
 
+fn test_samples_approx<F: Float + Display + Copy + PartialEq, D: Distribution<F>>(
+    seed: u64, distr: D, thresh: F, expected: &[F],
+) {
+    let mut rng = get_rng(seed);
+    for &val in expected {
+        let x = rng.sample(&distr);
+        assert!((x - val).abs() < thresh, "not approx eq: {}, {}", x, val);
+    }
+}
+
 #[test]
 fn binominal_stability() {
     // We have multiple code paths: np < 10, p > 0.5
@@ -95,7 +107,7 @@ fn pareto_stability() {
     test_samples(213, Pareto::new(1.0, 1.0).unwrap(), &[
         1.0423688f32, 2.1235929, 4.132709, 1.4679428,
     ]);
-    test_samples(213, Pareto::new(2.0, 0.5).unwrap(), &[
+    test_samples_approx(213, Pareto::new(2.0, 0.5).unwrap(), 1e-14, &[
         9.019295276219136f64,
         4.3097126018270595,
         6.837815045397157,
@@ -184,7 +196,7 @@ fn gamma_stability() {
         0.5013580219361969,
         0.1457735613733489,
     ]);
-    test_samples(223, ChiSquared::new(0.1).unwrap(), &[
+    test_samples_approx(223, ChiSquared::new(0.1).unwrap(), 1e-15, &[
         0.014824404726978617f64,
         0.021602123937134326,
         0.0000003431429746851693,
@@ -285,7 +297,7 @@ fn normal_stability() {
     test_samples(213, LogNormal::new(0.0, 1.0).unwrap(), &[
         0.88830346f32, 2.1844804, 1.0678421, 0.30322206,
     ]);
-    test_samples(213, LogNormal::new(2.0, 0.5).unwrap(), &[
+    test_samples_approx(213, LogNormal::new(2.0, 0.5).unwrap(), 1e-14, &[
         6.964174338639032f64,
         10.921015733601452,
         7.6355881556915906,