1 files changed, 53 insertions, 0 deletions
diff --git a/libcxx/test/numerics/rand/rand.dis/rand.dist.pois/rand.dist.pois.exp/eval.pass.cpp b/libcxx/test/numerics/rand/rand.dis/rand.dist.pois/rand.dist.pois.exp/eval.pass.cpp
new file mode 100644
index 00000000000..48cfc7ed628
--- /dev/null
+++ b/libcxx/test/numerics/rand/rand.dis/rand.dist.pois/rand.dist.pois.exp/eval.pass.cpp
@@ -0,0 +1,53 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <random>
+
+// template<class RealType = double>
+// class exponential_distribution
+
+// template<class _URNG> result_type operator()(_URNG& g);
+
+#include <random>
+#include <cassert>
+#include <vector>
+#include <numeric>
+
+template <class T>
+inline
+T
+sqr(T x)
+{
+    return x * x;
+}
+
+int main()
+{
+    {
+        typedef std::exponential_distribution<> D;
+        typedef D::param_type P;
+        typedef std::knuth_b G;
+        G g;
+        D d(.75);
+        const int N = 1000;
+        std::vector<D::result_type> u;
+        for (int i = 0; i < N; ++i)
+            u.push_back(d(g));
+        D::result_type mean = std::accumulate(u.begin(), u.end(),
+                                              D::result_type(0)) / u.size();
+        D::result_type var = 0;
+        for (int i = 0; i < u.size(); ++i)
+            var += sqr(u[i] - mean);
+        var /= u.size();
+        D::result_type x_mean = 1/d.lambda();
+        D::result_type x_var = 1/sqr(d.lambda());
+        assert(std::abs(mean - x_mean) / x_mean < 0.01);
+        assert(std::abs(var - x_var) / x_var < 0.01);
+    }
+}