From 29b57486871f39fc28a9e336ffc98e64afacc561 Mon Sep 17 00:00:00 2001
From: "Paul P.H. Wilson" <paul.wilson@wisc.edu>
Date: Fri, 17 Mar 2023 08:27:09 -0500
Subject: [PATCH] reduce temporary memory use for potentially large data

---
 include/openmc/distribution.h |  2 +-
 src/distribution.cpp          | 28 ++++++++++++++--------------
 2 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/include/openmc/distribution.h b/include/openmc/distribution.h
index 86aa4a3819..34744b3e3d 100644
--- a/include/openmc/distribution.h
+++ b/include/openmc/distribution.h
@@ -61,7 +61,7 @@ private:
   void normalize();
 
   //! Initialize alias tables for distribution
-  void init_alias(vector<double>& x, vector<double>& p);
+  void init_alias();
 };
 
 //==============================================================================
diff --git a/src/distribution.cpp b/src/distribution.cpp
index ce2a85705c..e2e1138265 100644
--- a/src/distribution.cpp
+++ b/src/distribution.cpp
@@ -26,38 +26,38 @@ Discrete::Discrete(pugi::xml_node node)
 {
   auto params = get_node_array<double>(node, "parameters");
 
-  std::size_t n = params.size();
-  std::vector<double> x_vec(params.begin(), params.begin() + n / 2);
-  std::vector<double> p_vec(params.begin() + n / 2, params.end());
+  std::size_t n = params.size()/2;
 
-  this->init_alias(x_vec, p_vec);
+  x_.assign(params.begin(), params.begin() + n);
+  prob_.assign(params.begin() + n, params.end());
+
+  this->init_alias();
 }
 
 Discrete::Discrete(const double* x, const double* p, int n)
 {
-  std::vector<double> x_vec(x, x + n);
-  std::vector<double> p_vec(p, p + n);
+  
+  x_.assign(x, x + n);
+  prob_.assign(p, p + n);
 
-  this->init_alias(x_vec, p_vec);
+  this->init_alias();
 }
 
 Discrete::Discrete(const double* p, int n)
 {
-  std::vector<double> p_vec(p, p + n);
-  std::vector<double> x_vec(n);
+  prob_.assign(p, p + n);
+  x_.resize(n);
 
   for (int i=0; i<n; i++) 
   {
-    x_vec[i] = i;
+    x_[i] = i;
   }
 
-  this->init_alias(x_vec, p_vec);
+  this->init_alias();
 }
 
-void Discrete::init_alias(vector<double>& x, vector<double>& p)
+void Discrete::init_alias()
 {
-  x_ = x;
-  prob_ = p;
   normalize();
 
   // The initialization and sampling method is based on Vose