Fix PR#20843: binomial_distribution<unsigned> is broken. Add test to ensure that signed and unsigned verstions produce the same sequence.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@217976 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/random b/include/random
index c0db1ab..e7053ce 100644
--- a/include/random
+++ b/include/random
@@ -4009,6 +4009,8 @@
}
}
+// Reference: Kemp, C.D. (1986). `A modal method for generating binomial
+// variables', Commun. Statist. - Theor. Meth. 15(3), 805-813.
template<class _IntType>
template<class _URNG>
_IntType
@@ -4035,7 +4037,8 @@
if (__u < 0)
return __rd - 1;
}
- --__rd;
+ if ( __rd != 0 )
+ --__rd;
++__ru;
if (__ru <= __pr.__t_)
{