From b74d57a52001bad39e29f0a4efc41150d53e0bbd Mon Sep 17 00:00:00 2001
From: paolo <paolo@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Fri, 25 Mar 2011 10:06:33 +0000
Subject: 2011-03-25 Paolo Carlini <paolo.carlini@oracle.com>
* include/bits/random.h (negative_binomial_distribution<>::
negative_binomial_distribution(_IntType, double),
negative_binomial_distribution<>::
negative_binomial_distribution(const param_type&)): Tweak
construction of _M_gd.
* include/bits/random.tcc (negative_binomial_distribution<>::
operator()): Adjust.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@171443 138bc75d-0d04-0410-961f-82ee72b054a4
---
libstdc++-v3/ChangeLog | 10 ++++++++++
libstdc++-v3/include/bits/random.h | 4 ++--
libstdc++-v3/include/bits/random.tcc | 11 +++++------
3 files changed, 17 insertions(+), 8 deletions(-)
diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 9182dc0ae4e..2facd17af70 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,13 @@
+2011-03-25 Paolo Carlini <paolo.carlini@oracle.com>
+
+ * include/bits/random.h (negative_binomial_distribution<>::
+ negative_binomial_distribution(_IntType, double),
+ negative_binomial_distribution<>::
+ negative_binomial_distribution(const param_type&)): Tweak
+ construction of _M_gd.
+ * include/bits/random.tcc (negative_binomial_distribution<>::
+ operator()): Adjust.
+
2011-03-24 Paolo Carlini <paolo.carlini@oracle.com>
* include/bits/random.h (negative_binomial_distribution<>::
diff --git a/libstdc++-v3/include/bits/random.h b/libstdc++-v3/include/bits/random.h
index 8b09a98c37b..7b7f5966b3c 100644
--- a/libstdc++-v3/include/bits/random.h
+++ b/libstdc++-v3/include/bits/random.h
@@ -3804,12 +3804,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
explicit
negative_binomial_distribution(_IntType __k = 1, double __p = 0.5)
- : _M_param(__k, __p), _M_gd(__k, 1.0)
+ : _M_param(__k, __p), _M_gd(__k, (1.0 - __p) / __p)
{ }
explicit
negative_binomial_distribution(const param_type& __p)
- : _M_param(__p), _M_gd(__p.k(), 1.0)
+ : _M_param(__p), _M_gd(__p.k(), (1.0 - __p.p()) / __p.p())
{ }
/**
diff --git a/libstdc++-v3/include/bits/random.tcc b/libstdc++-v3/include/bits/random.tcc
index 0bbc9fd400d..01ee5824cd9 100644
--- a/libstdc++-v3/include/bits/random.tcc
+++ b/libstdc++-v3/include/bits/random.tcc
@@ -1075,7 +1075,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return __is;
}
- // This is Leger's algorithm.
+ // This is Leger's algorithm, also in Devroye, Ch. X, Example 1.5.
template<typename _IntType>
template<typename _UniformRandomNumberGenerator>
typename negative_binomial_distribution<_IntType>::result_type
@@ -1085,8 +1085,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
const double __y = _M_gd(__urng);
// XXX Is the constructor too slow?
- std::poisson_distribution<result_type> __poisson(__y * (1.0 - p())
- / p());
+ std::poisson_distribution<result_type> __poisson(__y);
return __poisson(__urng);
}
@@ -1100,10 +1099,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
typedef typename std::gamma_distribution<result_type>::param_type
param_type;
- const double __y = _M_gd(__urng, param_type(__p.k(), 1.0));
+ const double __y =
+ _M_gd(__urng, param_type(__p.k(), (1.0 - __p.p()) / __p.p()));
- std::poisson_distribution<result_type> __poisson(__y * (1.0 - __p.p())
- / __p.p() );
+ std::poisson_distribution<result_type> __poisson(__y);
return __poisson(__urng);
}
--
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