From d1af74d0847a50574398c31e8732f86968f5b04e Mon Sep 17 00:00:00 2001
From: Reza Rastak <rastak@stanford.edu>
Date: Mon, 30 Dec 2019 12:48:58 -0800
Subject: [PATCH] mu_parser functions modified to use std random number
 generators

---
 doc/news/changes/minor/20191230RezaRastak     |  4 +++
 source/base/function_parser.cc                |  2 --
 source/base/mu_parser_internal.cc             | 27 ++++++++-----------
 source/base/tensor_function_parser.cc         |  2 --
 ...nction_parser_09.with_muparser=true.output |  2 +-
 ...nction_parser_10.with_muparser=true.output |  2 +-
 6 files changed, 17 insertions(+), 22 deletions(-)
 create mode 100644 doc/news/changes/minor/20191230RezaRastak

diff --git a/doc/news/changes/minor/20191230RezaRastak b/doc/news/changes/minor/20191230RezaRastak
new file mode 100644
index 0000000000..a902da5b68
--- /dev/null
+++ b/doc/news/changes/minor/20191230RezaRastak
@@ -0,0 +1,4 @@
+Improved: mu_parser functions now use random number generation facilities
+provided by the standard library.
+<br>
+(Reza Rastak, 2019/20/30)
diff --git a/source/base/function_parser.cc b/source/base/function_parser.cc
index 0a20249014..26bd537890 100644
--- a/source/base/function_parser.cc
+++ b/source/base/function_parser.cc
@@ -22,8 +22,6 @@
 
 #include <deal.II/lac/vector.h>
 
-#include <boost/random.hpp>
-
 #include <cmath>
 #include <map>
 
diff --git a/source/base/mu_parser_internal.cc b/source/base/mu_parser_internal.cc
index 9c4b964f23..74b9890d6e 100644
--- a/source/base/mu_parser_internal.cc
+++ b/source/base/mu_parser_internal.cc
@@ -16,12 +16,11 @@
 #include <deal.II/base/mu_parser_internal.h>
 #include <deal.II/base/thread_management.h>
 
-#include <boost/random.hpp>
-
 #include <cmath>
 #include <ctime>
 #include <map>
 #include <mutex>
+#include <random>
 #include <vector>
 
 
@@ -121,20 +120,17 @@ namespace internal
     double
     mu_rand_seed(double seed)
     {
-      static Threads::Mutex       rand_mutex;
+      static std::mutex           rand_mutex;
       std::lock_guard<std::mutex> lock(rand_mutex);
 
-      static boost::random::uniform_real_distribution<> uniform_distribution(0,
-                                                                             1);
+      std::uniform_real_distribution<> uniform_distribution(0., 1.);
 
-      // for each seed an unique random number generator is created,
+      // for each seed a unique random number generator is created,
       // which is initialized with the seed itself
-      // we could use std::mt19937 but doing so results in compiler-dependent
-      // output.
-      static std::map<double, boost::random::mt19937> rng_map;
+      static std::map<double, std::mt19937> rng_map;
 
       if (rng_map.find(seed) == rng_map.end())
-        rng_map[seed] = boost::random::mt19937(static_cast<unsigned int>(seed));
+        rng_map[seed] = std::mt19937(static_cast<unsigned int>(seed));
 
       return uniform_distribution(rng_map[seed]);
     }
@@ -143,12 +139,11 @@ namespace internal
     double
     mu_rand()
     {
-      static Threads::Mutex                             rand_mutex;
-      std::lock_guard<std::mutex>                       lock(rand_mutex);
-      static boost::random::uniform_real_distribution<> uniform_distribution(0,
-                                                                             1);
-      static boost::random::mt19937                     rng(
-                            static_cast<unsigned long>(std::time(nullptr)));
+      static std::mutex                rand_mutex;
+      std::lock_guard<std::mutex>      lock(rand_mutex);
+      std::uniform_real_distribution<> uniform_distribution(0., 1.);
+      const unsigned int  seed = static_cast<unsigned long>(std::time(nullptr));
+      static std::mt19937 rng(seed);
       return uniform_distribution(rng);
     }
 
diff --git a/source/base/tensor_function_parser.cc b/source/base/tensor_function_parser.cc
index eb4cb8c13c..f77927125d 100644
--- a/source/base/tensor_function_parser.cc
+++ b/source/base/tensor_function_parser.cc
@@ -22,8 +22,6 @@
 #include <deal.II/base/thread_management.h>
 #include <deal.II/base/utilities.h>
 
-#include <boost/random.hpp>
-
 #include <cmath>
 #include <map>
 
diff --git a/tests/base/function_parser_09.with_muparser=true.output b/tests/base/function_parser_09.with_muparser=true.output
index 59f845a429..03a86172f4 100644
--- a/tests/base/function_parser_09.with_muparser=true.output
+++ b/tests/base/function_parser_09.with_muparser=true.output
@@ -1,3 +1,3 @@
 
 DEAL::OK
-DEAL::0.771321
+DEAL::0.298761
diff --git a/tests/base/function_parser_10.with_muparser=true.output b/tests/base/function_parser_10.with_muparser=true.output
index 59f845a429..03a86172f4 100644
--- a/tests/base/function_parser_10.with_muparser=true.output
+++ b/tests/base/function_parser_10.with_muparser=true.output
@@ -1,3 +1,3 @@
 
 DEAL::OK
-DEAL::0.771321
+DEAL::0.298761
-- 
2.39.5