Make NaN propagatation consistent between the pmax/pmin and std::max/std::min. This makes the NaN propagation consistent between the scalar and vectorized code paths of Eigen's scalar_max_op and scalar_min_op.

See #1373 for details.

1 files changed, 46 insertions, 0 deletions

diff --git a/unsupported/test/cxx11_tensor_expr.cpp b/unsupported/test/cxx11_tensor_expr.cpp
index 77e24cb67..129b4e659 100644
--- a/unsupported/test/cxx11_tensor_expr.cpp
+++ b/unsupported/test/cxx11_tensor_expr.cpp
@@ -300,6 +300,51 @@ static void test_select()
   }
 }
 
+template <typename Scalar>
+void test_minmax_nan_propagation_templ() {
+  for (int size = 1; size < 17; ++size) {
+    const Scalar kNan = std::numeric_limits<Scalar>::quiet_NaN();
+    Tensor<Scalar, 1> vec_nan(size);
+    Tensor<Scalar, 1> vec_zero(size);
+    Tensor<Scalar, 1> vec_res(size);
+    vec_nan.setConstant(kNan);
+    vec_zero.setZero();
+    vec_res.setZero();
+
+    // Test that we propagate NaNs in the tensor when applying the
+    // cwiseMax(scalar) operator, which is used for the Relu operator.
+    vec_res = vec_nan.cwiseMax(Scalar(0));
+    for (int i = 0; i < size; ++i) {
+      VERIFY((numext::isnan)(vec_res(i)));
+    }
+
+    // Test that NaNs do not propagate if we reverse the arguments.
+    vec_res = vec_zero.cwiseMax(kNan);
+    for (int i = 0; i < size; ++i) {
+      VERIFY_IS_EQUAL(vec_res(i), Scalar(0));
+    }
+
+    // Test that we propagate NaNs in the tensor when applying the
+    // cwiseMin(scalar) operator.
+    vec_res.setZero();
+    vec_res = vec_nan.cwiseMin(Scalar(0));
+    for (int i = 0; i < size; ++i) {
+      VERIFY((numext::isnan)(vec_res(i)));
+    }
+
+    // Test that NaNs do not propagate if we reverse the arguments.
+    vec_res = vec_zero.cwiseMin(kNan);
+    for (int i = 0; i < size; ++i) {
+      VERIFY_IS_EQUAL(vec_res(i), Scalar(0));
+    }
+  }
+}
+
+static void test_minmax_nan_propagation()
+{
+  test_minmax_nan_propagation_templ<float>();
+  test_minmax_nan_propagation_templ<double>();
+}
 
 void test_cxx11_tensor_expr()
 {
@@ -311,4 +356,5 @@ void test_cxx11_tensor_expr()
   CALL_SUBTEST(test_functors());
   CALL_SUBTEST(test_type_casting());
   CALL_SUBTEST(test_select());
+  CALL_SUBTEST(test_minmax_nan_propagation());
 }