From 25f69cb932f05b8509df14d14d2779a20fc9b091 Mon Sep 17 00:00:00 2001
From: Benoit Steiner <benoit.steiner.goog@gmail.com>
Date: Fri, 11 Mar 2016 15:20:37 -0800
Subject: [PATCH] Added a comparison operator for Eigen::array Alias
 Eigen::array to std::array when compiling with Visual Studio 2015

---
 .../Eigen/CXX11/src/Core/util/EmulateArray.h      | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/unsupported/Eigen/CXX11/src/Core/util/EmulateArray.h b/unsupported/Eigen/CXX11/src/Core/util/EmulateArray.h
index eae8b996c..894b22009 100644
--- a/unsupported/Eigen/CXX11/src/Core/util/EmulateArray.h
+++ b/unsupported/Eigen/CXX11/src/Core/util/EmulateArray.h
@@ -15,7 +15,7 @@
 // The array class is only available starting with cxx11. Emulate our own here
 // if needed.
 // Moreover, CUDA doesn't support the STL containers, so we use our own instead.
-#if __cplusplus <= 199711L || defined(__CUDACC__) || defined(EIGEN_AVOID_STL_ARRAY)
+#if (__cplusplus <= 199711L && EIGEN_COMP_MSVC < 1900) || defined(__CUDACC__) || defined(EIGEN_AVOID_STL_ARRAY)
 
 namespace Eigen {
 template <typename T, size_t n> class array {
@@ -177,6 +177,19 @@ template <typename T> class array<T, 0> {
   T dummy;
 };
 
+// Comparison operator
+// Todo: implement !=, <, <=, >,  and >=
+template<class T, std::size_t N>
+bool operator==(const array<T,N>& lhs, const array<T,N>& rhs) {
+  for (std::size_t i = 0; i < N; ++i) {
+    if (lhs[i] != rhs[i]) {
+      return false;
+    }
+  }
+  return true;
+}
+
+
 namespace internal {
 template<std::size_t I, class T, std::size_t N>
 EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE T& array_get(array<T,N>& a) {