Improved the functors defined for standard reductions
Added a functor to encapsulate the generation of random numbers on cpu and gpu.

unsupported/Eigen/CXX11/src/Tensor/TensorFunctors.h

diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorFunctors.h b/unsupported/Eigen/CXX11/src/Tensor/TensorFunctors.h
index 9298433..e9aa221 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorFunctors.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorFunctors.h
@@ -25,12 +25,12 @@
   }
 
  private:
-  T m_sum;
+  typename internal::remove_all<T>::type m_sum;
 };
 
 template <typename T> struct MaxReducer
 {
-  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE MaxReducer() : m_max((std::numeric_limits<T>::min)()) { }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE MaxReducer() : m_max(-(std::numeric_limits<T>::max)()) { }
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void reduce(const T t) {
     if (t > m_max) { m_max = t; }
   }
@@ -39,7 +39,7 @@
   }
 
  private:
-  T m_max;
+  typename internal::remove_all<T>::type m_max;
 };
 
 template <typename T> struct MinReducer
@@ -53,9 +53,73 @@
   }
 
  private:
-  T m_min;
+  typename internal::remove_all<T>::type m_min;
 };
 
+
+#if !defined (EIGEN_USE_GPU) || !defined(__CUDACC__) || !defined(__CUDA_ARCH__)
+// We're not compiling a cuda kernel
+template <typename T> struct UniformRandomGenerator {
+  template<typename Index>
+  T operator()(Index, Index = 0) const {
+    return random<T>();
+  }
+  template<typename Index>
+  typename internal::packet_traits<T>::type packetOp(Index, Index = 0) const {
+    const int packetSize = internal::packet_traits<T>::size;
+    EIGEN_ALIGN_DEFAULT T values[packetSize];
+    for (int i = 0; i < packetSize; ++i) {
+      values[i] = random<T>();
+    }
+    return internal::pload<typename internal::packet_traits<T>::type>(values);
+  }
+};
+
+#else
+
+// We're compiling a cuda kernel
+template <typename T> struct UniformRandomGenerator;
+
+template <> struct UniformRandomGenerator<float> {
+  UniformRandomGenerator() {
+    const int tid = blockIdx.x * blockDim.x + threadIdx.x;
+    curand_init(0, tid, 0, &m_state);
+  }
+
+  template<typename Index>
+  float operator()(Index, Index = 0) const {
+    return curand_uniform(&m_state);
+  }
+  template<typename Index>
+  float4 packetOp(Index, Index = 0) const {
+    return curand_uniform4(&m_state);
+  }
+
+ private:
+  mutable curandStatePhilox4_32_10_t m_state;
+};
+
+template <> struct UniformRandomGenerator<double> {
+  UniformRandomGenerator() {
+    const int tid = blockIdx.x * blockDim.x + threadIdx.x;
+    curand_init(0, tid, 0, &m_state);
+  }
+  template<typename Index>
+  double operator()(Index, Index = 0) const {
+    return curand_uniform_double(&m_state);
+  }
+  template<typename Index>
+  double2 packetOp(Index, Index = 0) const {
+    return curand_uniform2_double(&m_state);
+  }
+
+ private:
+  mutable curandStatePhilox4_32_10_t m_state;
+};
+
+#endif
+
+
 } // end namespace internal
 } // end namespace Eigen
 

unsupported/test/cxx11_tensor_reduction.cpp

diff --git a/unsupported/test/cxx11_tensor_reduction.cpp b/unsupported/test/cxx11_tensor_reduction.cpp
index 27135b9..da98851 100644
--- a/unsupported/test/cxx11_tensor_reduction.cpp
+++ b/unsupported/test/cxx11_tensor_reduction.cpp
@@ -139,9 +139,42 @@
 }
 
 
+static void test_tensor_maps()
+{
+  int inputs[2*3*5*7];
+  TensorMap<Tensor<int, 4> > tensor_map(inputs, 2,3,5,7);
+  TensorMap<Tensor<const int, 4> > tensor_map_const(inputs, 2,3,5,7);
+  const TensorMap<Tensor<const int, 4> > tensor_map_const_const(inputs, 2,3,5,7);
+
+  tensor_map.setRandom();
+  array<ptrdiff_t, 2> reduction_axis;
+  reduction_axis[0] = 1;
+  reduction_axis[1] = 3;
+
+  Tensor<int, 2> result = tensor_map.sum(reduction_axis);
+  Tensor<int, 2> result2 = tensor_map_const.sum(reduction_axis);
+  Tensor<int, 2> result3 = tensor_map_const_const.sum(reduction_axis);
+
+  for (int i = 0; i < 2; ++i) {
+    for (int j = 0; j < 5; ++j) {
+      int sum = 0;
+      for (int k = 0; k < 3; ++k) {
+        for (int l = 0; l < 7; ++l) {
+          sum += tensor_map(i, k, j, l);
+        }
+      }
+      VERIFY_IS_EQUAL(result(i, j), sum);
+      VERIFY_IS_EQUAL(result2(i, j), sum);
+      VERIFY_IS_EQUAL(result3(i, j), sum);
+    }
+  }
+}
+
+
 void test_cxx11_tensor_reduction()
 {
    CALL_SUBTEST(test_simple_reductions());
    CALL_SUBTEST(test_full_reductions());
    CALL_SUBTEST(test_user_defined_reductions());
+   CALL_SUBTEST(test_tensor_maps());
 }