text: // This file is part of Eigen, a lightweight C++ template library
  // for linear algebra.
  //
  // Copyright (C) 2014 Benoit Steiner <benoit.steiner.goog@gmail.com>
  //
  // This Source Code Form is subject to the terms of the Mozilla
  // Public License v. 2.0. If a copy of the MPL was not distributed
  // with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
  
  #include "main.h"
  
  #include <Eigen/CXX11/Tensor>
  
  using Eigen::Tensor;
  
  template<int DataLayout>
  static void test_simple_striding()
  {
    Tensor<float, 4, DataLayout> tensor(2,3,5,7);
    tensor.setRandom();
    array<ptrdiff_t, 4> strides;
    strides[0] = 1;
    strides[1] = 1;
    strides[2] = 1;
    strides[3] = 1;
  
    Tensor<float, 4, DataLayout> no_stride;
    no_stride = tensor.stride(strides);
  
    VERIFY_IS_EQUAL(no_stride.dimension(0), 2);
    VERIFY_IS_EQUAL(no_stride.dimension(1), 3);
    VERIFY_IS_EQUAL(no_stride.dimension(2), 5);
    VERIFY_IS_EQUAL(no_stride.dimension(3), 7);
  
    for (int i = 0; i < 2; ++i) {
      for (int j = 0; j < 3; ++j) {
        for (int k = 0; k < 5; ++k) {
          for (int l = 0; l < 7; ++l) {
            VERIFY_IS_EQUAL(tensor(i,j,k,l), no_stride(i,j,k,l));
          }
        }
      }
    }
  
    strides[0] = 2;
    strides[1] = 4;
    strides[2] = 2;
    strides[3] = 3;
    Tensor<float, 4, DataLayout> stride;
    stride = tensor.stride(strides);
  
    VERIFY_IS_EQUAL(stride.dimension(0), 1);
    VERIFY_IS_EQUAL(stride.dimension(1), 1);
    VERIFY_IS_EQUAL(stride.dimension(2), 3);
    VERIFY_IS_EQUAL(stride.dimension(3), 3);
  
    for (int i = 0; i < 1; ++i) {
      for (int j = 0; j < 1; ++j) {
        for (int k = 0; k < 3; ++k) {
          for (int l = 0; l < 3; ++l) {
            VERIFY_IS_EQUAL(tensor(2*i,4*j,2*k,3*l), stride(i,j,k,l));
          }
        }
      }
    }
  }
  
  
  template<int DataLayout>
  static void test_striding_as_lvalue()
  {
    Tensor<float, 4, DataLayout> tensor(2,3,5,7);
    tensor.setRandom();
    array<ptrdiff_t, 4> strides;
    strides[0] = 2;
    strides[1] = 4;
    strides[2] = 2;
    strides[3] = 3;
  
    Tensor<float, 4, DataLayout> result(3, 12, 10, 21);
    result.stride(strides) = tensor;
  
    for (int i = 0; i < 2; ++i) {
      for (int j = 0; j < 3; ++j) {
        for (int k = 0; k < 5; ++k) {
          for (int l = 0; l < 7; ++l) {
            VERIFY_IS_EQUAL(tensor(i,j,k,l), result(2*i,4*j,2*k,3*l));
          }
        }
      }
    }
  
    array<ptrdiff_t, 4> no_strides;
    no_strides[0] = 1;
    no_strides[1] = 1;
    no_strides[2] = 1;
    no_strides[3] = 1;
    Tensor<float, 4, DataLayout> result2(3, 12, 10, 21);
    result2.stride(strides) = tensor.stride(no_strides);
  
    for (int i = 0; i < 2; ++i) {
      for (int j = 0; j < 3; ++j) {
        for (int k = 0; k < 5; ++k) {
          for (int l = 0; l < 7; ++l) {
            VERIFY_IS_EQUAL(tensor(i,j,k,l), result2(2*i,4*j,2*k,3*l));
          }
        }
      }
    }
  }
  
  
  void test_cxx11_tensor_striding()
  {
    CALL_SUBTEST(test_simple_striding<ColMajor>());
    CALL_SUBTEST(test_simple_striding<RowMajor>());
    CALL_SUBTEST(test_striding_as_lvalue<ColMajor>());
    CALL_SUBTEST(test_striding_as_lvalue<RowMajor>());
  }
  