From f1173e82c1c5786e0ad4debdb5b0ae7d09c45d8a Mon Sep 17 00:00:00 2001
From: Paul Romano <paul.k.romano@gmail.com>
Date: Thu, 13 May 2021 07:18:46 -0500
Subject: [PATCH] Address @jtramm comments

---
 src/random_dist.cpp          | 32 +++++++++++++++++---------------
 src/random_lcg.cpp           |  2 +-
 tests/unit_tests/test_lib.py |  2 +-
 3 files changed, 19 insertions(+), 17 deletions(-)

diff --git a/src/random_dist.cpp b/src/random_dist.cpp
index 3966cf5d82..c8d2380c36 100644
--- a/src/random_dist.cpp
+++ b/src/random_dist.cpp
@@ -9,11 +9,11 @@ namespace openmc {
 
 double uniform_distribution(double a, double b, uint64_t* seed)
 {
-    return a + (b - a)*prn(seed);
+  return a + (b - a) * prn(seed);
 }
 
-
-double maxwell_spectrum(double T, uint64_t* seed) {
+double maxwell_spectrum(double T, uint64_t* seed)
+{
   // Set the random numbers
   double r1 = prn(seed);
   double r2 = prn(seed);
@@ -26,28 +26,30 @@ double maxwell_spectrum(double T, uint64_t* seed) {
   return -T * (std::log(r1) + std::log(r2) * c * c);
 }
 
-double watt_spectrum(double a, double b, uint64_t* seed) {
+double watt_spectrum(double a, double b, uint64_t* seed)
+{
   double w = maxwell_spectrum(a, seed);
-  return w + 0.25 * a * a * b + (2. * prn(seed) - 1.) * std::sqrt(a * a * b * w);
+  return w + 0.25 * a * a * b +
+         uniform_distribution(-1., 1., seed) * std::sqrt(a * a * b * w);
 }
 
-
-double normal_variate(double mean, double standard_deviation, uint64_t* seed) {
+double normal_variate(double mean, double standard_deviation, uint64_t* seed)
+{
   // Sample a normal variate using Marsaglia's polar method
   double x, y, r2;
   do {
-    x = 2 * prn(seed) - 1.;
-    y = 2 * prn(seed) - 1.;
-    r2 = x*x + y*y;
+    x = uniform_distribution(-1., 1., seed);
+    y = uniform_distribution(-1., 1., seed);
+    r2 = x * x + y * y;
   } while (r2 > 1 || r2 == 0);
-  double z = std::sqrt(-2.0 * std::log(r2)/r2);
-  return mean + standard_deviation*z*x;
+  double z = std::sqrt(-2.0 * std::log(r2) / r2);
+  return mean + standard_deviation * z * x;
 }
 
-
-double muir_spectrum(double e0, double m_rat, double kt, uint64_t* seed) {
+double muir_spectrum(double e0, double m_rat, double kt, uint64_t* seed)
+{
   // https://permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-05411-MS
-  double sigma = std::sqrt(4.*e0*kt/m_rat);
+  double sigma = std::sqrt(4. * e0 * kt / m_rat);
   return normal_variate(e0, sigma, seed);
 }
 
diff --git a/src/random_lcg.cpp b/src/random_lcg.cpp
index c3bd0d5add..38174be657 100644
--- a/src/random_lcg.cpp
+++ b/src/random_lcg.cpp
@@ -11,7 +11,7 @@ int64_t master_seed {1};
 // LCG parameters
 constexpr uint64_t prn_mult   {6364136223846793005ULL};  // multiplication
 constexpr uint64_t prn_add    {1442695040888963407ULL};  // additive factor, c
-constexpr uint64_t prn_stride {152917LL};                // stride between
+constexpr uint64_t prn_stride {152917LL};                // stride between particles
 
 //==============================================================================
 // PRN
diff --git a/tests/unit_tests/test_lib.py b/tests/unit_tests/test_lib.py
index d1c07ce716..87d4843c77 100644
--- a/tests/unit_tests/test_lib.py
+++ b/tests/unit_tests/test_lib.py
@@ -390,7 +390,7 @@ def test_reset(lib_run):
         for i in range(20):
             openmc.lib.next_batch()
 
-        # Make sure there are 5 realizations for the 5 active batches.
+        # Make sure there are 15 realizations for the 15 active batches.
         assert openmc.lib.num_realizations() == 15
         assert openmc.lib.tallies[2].num_realizations == 15
         _, keff_sd1 = openmc.lib.keff()