Changeset 5906

Timestamp:

01/31/08 00:09:35 (5 years ago)

Author:

mrkn

Message:

lang/cplusplus/boost-supplement/trunk/boost_supplement/random/discrete_distribution.hpp (boost_supplement::discrete_distribution): Adds a comment about Walker's original paper of the algorithm for this class. Some lines are moved for easy reading. An assertion is added.

Location:

lang/cplusplus/boost-supplement/trunk

Files:

• ChangeLog (modified) (1 diff)
• boost_supplement/random/discrete_distribution.hpp (modified) (5 diffs)

lang/cplusplus/boost-supplement/trunk/ChangeLog

@@ +1 @@
+2008-01-31  Kenta Murata  <muraken@gmail.com>
+
+        * boost_supplement/random/discrete_distribution.hpp
+        (boost_supplement::discrete_distribution): Adds a comment about
+        Walker's original paper of the algorithm for this class.
+        Some lines are moved for easy reading. An assertion is added.
+
 2008-01-30  Kenta Murata  <muraken@gmail.com>
 

lang/cplusplus/boost-supplement/trunk/boost_supplement/random/discrete_distribution.hpp

@@ -21 +21 @@
 
 namespace boost_supplement {
+
+/* Alastair J. Walker.  An Efficient Method for Generating Discrete
+ * Random Variables With General Distributions.  ACM TOMS 3(3),
+ * 253--256 (1977). */
 template<class IntType = long, class RealType = double>
 class discrete_distribution
@@ -28 +32 @@
   typedef IntType result_type;
 
+#if !defined(BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS) && !(defined(BOOST_MSVC) && BOOST_MSVC <= 1300)
+  BOOST_STATIC_ASSERT(std::numeric_limits<IntType>::is_integer);
+  BOOST_STATIC_ASSERT(!std::numeric_limits<RealType>::is_integer);
+#endif
+
   typedef typename std::vector<input_type>::const_iterator probability_iterator;
   typedef typename std::vector<input_type>::const_reverse_iterator probability_reverse_iterator;
@@ -33 +42 @@
   typedef typename std::vector<result_type>::const_iterator alias_iterator;
   typedef typename std::vector<result_type>::const_reverse_iterator alias_reverse_iterator;
-
-#if !defined(BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS) && !(defined(BOOST_MSVC) && BOOST_MSVC <= 1300)
-  BOOST_STATIC_ASSERT(std::numeric_limits<IntType>::is_integer);
-  BOOST_STATIC_ASSERT(!std::numeric_limits<RealType>::is_integer);
-#endif
 
 private:
@@ -51 +55 @@
 
       result_type n = std::distance(first, last);
-      aliases_.resize(n, n);
+      BOOST_ASSERT(0 < n);
 
       while (first != last) {
@@ -57 +61 @@
         ++first;
       }
+      BOOST_ASSERT(n == probabilities_.size());
 
-      BOOST_ASSERT(n == probabilities_.size());
+      aliases_.resize(n, n);
 
       for (result_type i = 0; i < n; ++i) {