Merge changes Iee153445,Iee274471 am: 79df15ea88 am: 10f298fc41

Original change: https://android-review.googlesource.com/c/platform/external/eigen/+/1999079

Change-Id: I3dd349f9a45d37f37441ff7a7742ebe953b70516

1 files changed, 32 insertions, 1 deletions

diff --git a/unsupported/test/cxx11_tensor_fft.cpp b/unsupported/test/cxx11_tensor_fft.cpp
index 2f14ebc62..2e1008eca 100644
--- a/unsupported/test/cxx11_tensor_fft.cpp
+++ b/unsupported/test/cxx11_tensor_fft.cpp
@@ -224,7 +224,35 @@ static void test_fft_real_input_energy() {
   }
 }
 
-void test_cxx11_tensor_fft() {
+template <typename RealScalar>
+static void test_fft_non_power_of_2_round_trip(int exponent) {
+  int n = (1 << exponent) + 1;
+
+  Eigen::DSizes<ptrdiff_t, 1> dimensions;
+  dimensions[0] = n;
+  const DSizes<ptrdiff_t, 1> arr = dimensions;
+  Tensor<RealScalar, 1, ColMajor, ptrdiff_t> input;
+
+  input.resize(arr);
+  input.setRandom();
+
+  array<int, 1> fft;
+  fft[0] = 0;
+
+  Tensor<std::complex<RealScalar>, 1, ColMajor> forward =
+      input.template fft<BothParts, FFT_FORWARD>(fft);
+
+  Tensor<RealScalar, 1, ColMajor, ptrdiff_t> output =
+      forward.template fft<RealPart, FFT_REVERSE>(fft);
+
+  for (int i = 0; i < n; ++i) {
+    RealScalar tol = test_precision<RealScalar>() *
+                     (std::abs(input[i]) + std::abs(output[i]) + 1);
+    VERIFY_IS_APPROX_OR_LESS_THAN(std::abs(input[i] - output[i]), tol);
+  }
+}
+
+EIGEN_DECLARE_TEST(cxx11_tensor_fft) {
     test_fft_complex_input_golden();
     test_fft_real_input_golden();
 
@@ -270,4 +298,7 @@ void test_cxx11_tensor_fft() {
     test_fft_real_input_energy<RowMajor, double, true,  Eigen::BothParts, FFT_FORWARD, 4>();
     test_fft_real_input_energy<RowMajor, float,  false,  Eigen::BothParts, FFT_FORWARD, 4>();
     test_fft_real_input_energy<RowMajor, double, false,  Eigen::BothParts, FFT_FORWARD, 4>();
+
+    test_fft_non_power_of_2_round_trip<float>(7);
+    test_fft_non_power_of_2_round_trip<double>(7);
 }