stl_iterators.cpp File Reference

#include "main.h"
#include <iterator>
#include <numeric>

Functions
template<class Iterator >
std::reverse_iterator< Iterator >	make_reverse_iterator (Iterator i)
template<typename XprType >
bool	is_pointer_based_stl_iterator (const internal::pointer_based_stl_iterator< XprType > &)
template<typename XprType >
bool	is_generic_randaccess_stl_iterator (const internal::generic_randaccess_stl_iterator< XprType > &)
template<typename Iter >
bool	is_default_constructible_and_assignable (const Iter &it)
template<typename Xpr >
void	check_begin_end_for_loop (Xpr xpr)
template<typename Scalar , int Rows, int Cols>
void	test_stl_iterators (int rows=Rows, int cols=Cols)
template<class C , class Iterator = decltype(::std::declval<const C&>().begin()), class = decltype(::std::declval<const C&>().end()), class = decltype(++::std::declval<Iterator&>()), class = decltype(*::std::declval<Iterator>()), class = typename C::const_iterator>
bool	IsContainerType (int)
template<class C >
bool	IsContainerType (long)
template<typename Scalar , int Rows, int Cols>
void	test_stl_container_detection (int rows=Rows, int cols=Cols)
	EIGEN_DECLARE_TEST (stl_iterators)

Function Documentation

check_begin_end_for_loop()

template<typename Xpr >

void check_begin_end_for_loop

(

Xpr

xpr

)

                                       {
  const Xpr& cxpr(xpr);
  Index i = 0;
 
  i = 0;
  for (typename Xpr::iterator it = xpr.begin(); it != xpr.end(); ++it) {
    VERIFY_IS_EQUAL(*it, xpr[i++]);
  }
 
  i = 0;
  for (typename Xpr::const_iterator it = xpr.cbegin(); it != xpr.cend(); ++it) {
    VERIFY_IS_EQUAL(*it, xpr[i++]);
  }
 
  i = 0;
  for (typename Xpr::const_iterator it = cxpr.begin(); it != cxpr.end(); ++it) {
    VERIFY_IS_EQUAL(*it, xpr[i++]);
  }
 
  i = 0;
  for (typename Xpr::const_iterator it = xpr.begin(); it != xpr.end(); ++it) {
    VERIFY_IS_EQUAL(*it, xpr[i++]);
  }
 
  {
    // simple API check
    typename Xpr::const_iterator cit = xpr.begin();
    cit = xpr.cbegin();
 
    auto tmp1 = xpr.begin();
    VERIFY(tmp1 == xpr.begin());
    auto tmp2 = xpr.cbegin();
    VERIFY(tmp2 == xpr.cbegin());
  }
 
  VERIFY(xpr.end() - xpr.begin() == xpr.size());
  VERIFY(xpr.cend() - xpr.begin() == xpr.size());
  VERIFY(xpr.end() - xpr.cbegin() == xpr.size());
  VERIFY(xpr.cend() - xpr.cbegin() == xpr.size());
 
  if (xpr.size() > 0) {
    VERIFY(xpr.begin() != xpr.end());
    VERIFY(xpr.begin() < xpr.end());
    VERIFY(xpr.begin() <= xpr.end());
    VERIFY(!(xpr.begin() == xpr.end()));
    VERIFY(!(xpr.begin() > xpr.end()));
    VERIFY(!(xpr.begin() >= xpr.end()));
 
    VERIFY(xpr.cbegin() != xpr.end());
    VERIFY(xpr.cbegin() < xpr.end());
    VERIFY(xpr.cbegin() <= xpr.end());
    VERIFY(!(xpr.cbegin() == xpr.end()));
    VERIFY(!(xpr.cbegin() > xpr.end()));
    VERIFY(!(xpr.cbegin() >= xpr.end()));
 
    VERIFY(xpr.begin() != xpr.cend());
    VERIFY(xpr.begin() < xpr.cend());
    VERIFY(xpr.begin() <= xpr.cend());
    VERIFY(!(xpr.begin() == xpr.cend()));
    VERIFY(!(xpr.begin() > xpr.cend()));
    VERIFY(!(xpr.begin() >= xpr.cend()));
  }
}

References i, VERIFY, and VERIFY_IS_EQUAL.

Referenced by test_stl_iterators().

EIGEN_DECLARE_TEST()

EIGEN_DECLARE_TEST

(

stl_iterators

)

                                  {
  for (int i = 0; i < g_repeat; i++) {
    CALL_SUBTEST_1((test_stl_iterators<double, 2, 3>()));
    CALL_SUBTEST_1((test_stl_iterators<float, 7, 5>()));
    CALL_SUBTEST_1(
        (test_stl_iterators<int, Dynamic, Dynamic>(internal::random<int>(5, 10), internal::random<int>(5, 10))));
    CALL_SUBTEST_1(
        (test_stl_iterators<int, Dynamic, Dynamic>(internal::random<int>(10, 200), internal::random<int>(10, 200))));
  }
 
  CALL_SUBTEST_1((test_stl_container_detection<float, 1, 1>()));
  CALL_SUBTEST_1((test_stl_container_detection<float, 5, 5>()));
}

References CALL_SUBTEST_1, Eigen::g_repeat, and i.

is_default_constructible_and_assignable()

template<typename Iter >

bool is_default_constructible_and_assignable

(

const Iter &

it

)

                                                             {
  VERIFY(std::is_default_constructible<Iter>::value);
  VERIFY(std::is_nothrow_default_constructible<Iter>::value);
  Iter it2;
  it2 = it;
  return (it == it2);
}

References Eigen::value, and VERIFY.

Referenced by test_stl_iterators().

is_generic_randaccess_stl_iterator()

template<typename XprType >

bool is_generic_randaccess_stl_iterator

(

const internal::generic_randaccess_stl_iterator< XprType > &

)

                                                                                                 {
  return true;
}

Referenced by test_stl_iterators().

is_pointer_based_stl_iterator()

template<typename XprType >

bool is_pointer_based_stl_iterator

(

const internal::pointer_based_stl_iterator< XprType > &

)

                                                                                       {
  return true;
}

Referenced by test_stl_iterators().

IsContainerType() [1/2]

template<class C , class Iterator = decltype(::std::declval<const C&>().begin()), class = decltype(::std::declval<const C&>().end()), class = decltype(++::std::declval<Iterator&>()), class = decltype(*::std::declval<Iterator>()), class = typename C::const_iterator>

bool IsContainerType

(

int

)

                            {
  return true;
}

IsContainerType() [2/2]

template<class C >

bool IsContainerType

(

long

)

                             {
  return false;
}

make_reverse_iterator()

template<class Iterator >

std::reverse_iterator<Iterator> make_reverse_iterator

(

Iterator

i

)

                                                                {
  return std::reverse_iterator<Iterator>(i);
}

References i.

Referenced by test_stl_iterators().

test_stl_container_detection()

template<typename Scalar , int Rows, int Cols>

void test_stl_container_detection	(	int	rows = Rows,
		int	cols = Cols
	)

                                                                    {
  typedef Matrix<Scalar, Rows, 1> VectorType;
  typedef Matrix<Scalar, Rows, Cols, ColMajor> ColMatrixType;
  typedef Matrix<Scalar, Rows, Cols, RowMajor> RowMatrixType;
 
  ColMatrixType A = ColMatrixType::Random(rows, cols);
  RowMatrixType B = RowMatrixType::Random(rows, cols);
 
  Index i = 1;
 
  using ColMatrixColType = decltype(A.col(i));
  using ColMatrixRowType = decltype(A.row(i));
  using RowMatrixColType = decltype(B.col(i));
  using RowMatrixRowType = decltype(B.row(i));
 
  // Vector and matrix col/row are valid Stl-style container.
  VERIFY_IS_EQUAL(IsContainerType<VectorType>(0), true);
  VERIFY_IS_EQUAL(IsContainerType<ColMatrixColType>(0), true);
  VERIFY_IS_EQUAL(IsContainerType<ColMatrixRowType>(0), true);
  VERIFY_IS_EQUAL(IsContainerType<RowMatrixColType>(0), true);
  VERIFY_IS_EQUAL(IsContainerType<RowMatrixRowType>(0), true);
 
  // But the matrix itself is not a valid Stl-style container.
  VERIFY_IS_EQUAL(IsContainerType<ColMatrixType>(0), rows == 1 || cols == 1);
  VERIFY_IS_EQUAL(IsContainerType<RowMatrixType>(0), rows == 1 || cols == 1);
}

References cols, i, rows, and VERIFY_IS_EQUAL.

test_stl_iterators()

template<typename Scalar , int Rows, int Cols>

void test_stl_iterators	(	int	rows = Rows,
		int	cols = Cols
	)

                                                          {
  typedef Matrix<Scalar, Rows, 1> VectorType;
  typedef Matrix<Scalar, 1, Cols> RowVectorType;
  typedef Matrix<Scalar, Rows, Cols, ColMajor> ColMatrixType;
  typedef Matrix<Scalar, Rows, Cols, RowMajor> RowMatrixType;
  VectorType v = VectorType::Random(rows);
  const VectorType& cv(v);
  ColMatrixType A = ColMatrixType::Random(rows, cols);
  const ColMatrixType& cA(A);
  RowMatrixType B = RowMatrixType::Random(rows, cols);
  using Eigen::placeholders::last;
 
  Index i, j;
 
  // Verify that iterators are default constructible (See bug #1900)
  {
    VERIFY(is_default_constructible_and_assignable(v.begin()));
    VERIFY(is_default_constructible_and_assignable(v.end()));
    VERIFY(is_default_constructible_and_assignable(cv.begin()));
    VERIFY(is_default_constructible_and_assignable(cv.end()));
 
    VERIFY(is_default_constructible_and_assignable(A.row(0).begin()));
    VERIFY(is_default_constructible_and_assignable(A.row(0).end()));
    VERIFY(is_default_constructible_and_assignable(cA.row(0).begin()));
    VERIFY(is_default_constructible_and_assignable(cA.row(0).end()));
 
    VERIFY(is_default_constructible_and_assignable(B.row(0).begin()));
    VERIFY(is_default_constructible_and_assignable(B.row(0).end()));
  }
 
  // Check we got a fast pointer-based iterator when expected
  {
    VERIFY(is_pointer_based_stl_iterator(v.begin()));
    VERIFY(is_pointer_based_stl_iterator(v.end()));
    VERIFY(is_pointer_based_stl_iterator(cv.begin()));
    VERIFY(is_pointer_based_stl_iterator(cv.end()));
 
    j = internal::random<Index>(0, A.cols() - 1);
    VERIFY(is_pointer_based_stl_iterator(A.col(j).begin()));
    VERIFY(is_pointer_based_stl_iterator(A.col(j).end()));
    VERIFY(is_pointer_based_stl_iterator(cA.col(j).begin()));
    VERIFY(is_pointer_based_stl_iterator(cA.col(j).end()));
 
    i = internal::random<Index>(0, A.rows() - 1);
    VERIFY(is_pointer_based_stl_iterator(A.row(i).begin()));
    VERIFY(is_pointer_based_stl_iterator(A.row(i).end()));
    VERIFY(is_pointer_based_stl_iterator(cA.row(i).begin()));
    VERIFY(is_pointer_based_stl_iterator(cA.row(i).end()));
 
    VERIFY(is_pointer_based_stl_iterator(A.reshaped().begin()));
    VERIFY(is_pointer_based_stl_iterator(A.reshaped().end()));
    VERIFY(is_pointer_based_stl_iterator(cA.reshaped().begin()));
    VERIFY(is_pointer_based_stl_iterator(cA.reshaped().end()));
 
    VERIFY(is_pointer_based_stl_iterator(B.template reshaped<AutoOrder>().begin()));
    VERIFY(is_pointer_based_stl_iterator(B.template reshaped<AutoOrder>().end()));
 
    VERIFY(is_generic_randaccess_stl_iterator(A.template reshaped<RowMajor>().begin()));
    VERIFY(is_generic_randaccess_stl_iterator(A.template reshaped<RowMajor>().end()));
  }
 
  {
    check_begin_end_for_loop(v);
    check_begin_end_for_loop(A.col(internal::random<Index>(0, A.cols() - 1)));
    check_begin_end_for_loop(A.row(internal::random<Index>(0, A.rows() - 1)));
    check_begin_end_for_loop(v + v);
  }
 
  // check swappable
  {
    using std::swap;
    // pointer-based
    {
      VectorType v_copy = v;
      auto a = v.begin();
      auto b = v.end() - 1;
      swap(a, b);
      VERIFY_IS_EQUAL(v, v_copy);
      VERIFY_IS_EQUAL(*b, *v.begin());
      VERIFY_IS_EQUAL(*b, v(0));
      VERIFY_IS_EQUAL(*a, v.end()[-1]);
      VERIFY_IS_EQUAL(*a, v(last));
    }
 
    // generic
    {
      RowMatrixType B_copy = B;
      auto Br = B.reshaped();
      auto a = Br.begin();
      auto b = Br.end() - 1;
      swap(a, b);
      VERIFY_IS_EQUAL(B, B_copy);
      VERIFY_IS_EQUAL(*b, *Br.begin());
      VERIFY_IS_EQUAL(*b, Br(0));
      VERIFY_IS_EQUAL(*a, Br.end()[-1]);
      VERIFY_IS_EQUAL(*a, Br(last));
    }
  }
 
  // check non-const iterator with for-range loops
  {
    i = 0;
    for (auto x : v) {
      VERIFY_IS_EQUAL(x, v[i++]);
    }
 
    j = internal::random<Index>(0, A.cols() - 1);
    i = 0;
    for (auto x : A.col(j)) {
      VERIFY_IS_EQUAL(x, A(i++, j));
    }
 
    i = 0;
    for (auto x : (v + A.col(j))) {
      VERIFY_IS_APPROX(x, v(i) + A(i, j));
      ++i;
    }
 
    j = 0;
    i = internal::random<Index>(0, A.rows() - 1);
    for (auto x : A.row(i)) {
      VERIFY_IS_EQUAL(x, A(i, j++));
    }
 
    i = 0;
    for (auto x : A.reshaped()) {
      VERIFY_IS_EQUAL(x, A(i++));
    }
  }
 
  // same for const_iterator
  {
    i = 0;
    for (auto x : cv) {
      VERIFY_IS_EQUAL(x, v[i++]);
    }
 
    i = 0;
    for (auto x : cA.reshaped()) {
      VERIFY_IS_EQUAL(x, A(i++));
    }
 
    j = 0;
    i = internal::random<Index>(0, A.rows() - 1);
    for (auto x : cA.row(i)) {
      VERIFY_IS_EQUAL(x, A(i, j++));
    }
  }
 
  // check reshaped() on row-major
  {
    i = 0;
    Matrix<Scalar, Dynamic, Dynamic, ColMajor> Bc = B;
    for (auto x : B.reshaped()) {
      VERIFY_IS_EQUAL(x, Bc(i++));
    }
  }
 
  // check write access
  {
    VectorType w(v.size());
    i = 0;
    for (auto& x : w) {
      x = v(i++);
    }
    VERIFY_IS_EQUAL(v, w);
  }
 
  // check for dangling pointers
  {
    // no dangling because pointer-based
    {
      j = internal::random<Index>(0, A.cols() - 1);
      auto it = A.col(j).begin();
      for (i = 0; i < rows; ++i) {
        VERIFY_IS_EQUAL(it[i], A(i, j));
      }
    }
 
    // no dangling because pointer-based
    {
      i = internal::random<Index>(0, A.rows() - 1);
      auto it = A.row(i).begin();
      for (j = 0; j < cols; ++j) {
        VERIFY_IS_EQUAL(it[j], A(i, j));
      }
    }
 
    {
      j = internal::random<Index>(0, A.cols() - 1);
      // this would produce a dangling pointer:
      // auto it = (A+2*A).col(j).begin();
      // we need to name the temporary expression:
      auto tmp = (A + 2 * A).col(j);
      auto it = tmp.begin();
      for (i = 0; i < rows; ++i) {
        VERIFY_IS_APPROX(it[i], 3 * A(i, j));
      }
    }
  }
 
  {
    // check basic for loop on vector-wise iterators
    j = 0;
    for (auto it = A.colwise().cbegin(); it != A.colwise().cend(); ++it, ++j) {
      VERIFY_IS_APPROX(it->coeff(0), A(0, j));
      VERIFY_IS_APPROX((*it).coeff(0), A(0, j));
    }
    j = 0;
    for (auto it = A.colwise().begin(); it != A.colwise().end(); ++it, ++j) {
      (*it).coeffRef(0) = (*it).coeff(0);  // compilation check
      it->coeffRef(0) = it->coeff(0);      // compilation check
      VERIFY_IS_APPROX(it->coeff(0), A(0, j));
      VERIFY_IS_APPROX((*it).coeff(0), A(0, j));
    }
 
    // check valuetype gives us a copy
    j = 0;
    for (auto it = A.colwise().cbegin(); it != A.colwise().cend(); ++it, ++j) {
      typename decltype(it)::value_type tmp = *it;
      VERIFY_IS_NOT_EQUAL(tmp.data(), it->data());
      VERIFY_IS_APPROX(tmp, A.col(j));
    }
  }
 
  if (rows >= 3) {
    VERIFY_IS_EQUAL((v.begin() + rows / 2)[1], v(rows / 2 + 1));
 
    VERIFY_IS_EQUAL((A.rowwise().begin() + rows / 2)[1], A.row(rows / 2 + 1));
  }
 
  if (cols >= 3) {
    VERIFY_IS_EQUAL((A.colwise().begin() + cols / 2)[1], A.col(cols / 2 + 1));
  }
 
  // check std::sort
  {
    // first check that is_sorted returns false when required
    if (rows >= 2) {
      v(1) = v(0) - Scalar(1);
      VERIFY(!is_sorted(std::begin(v), std::end(v)));
    }
 
    // on a vector
    {
      std::sort(v.begin(), v.end());
      VERIFY(is_sorted(v.begin(), v.end()));
      VERIFY(!::is_sorted(make_reverse_iterator(v.end()), make_reverse_iterator(v.begin())));
    }
 
    // on a column of a column-major matrix -> pointer-based iterator and default increment
    {
      j = internal::random<Index>(0, A.cols() - 1);
      // std::sort(begin(A.col(j)),end(A.col(j))); // does not compile because this returns const iterators
      typename ColMatrixType::ColXpr Acol = A.col(j);
      std::sort(Acol.begin(), Acol.end());
      VERIFY(is_sorted(Acol.cbegin(), Acol.cend()));
      A.setRandom();
 
      std::sort(A.col(j).begin(), A.col(j).end());
      VERIFY(is_sorted(A.col(j).cbegin(), A.col(j).cend()));
      A.setRandom();
    }
 
    // on a row of a rowmajor matrix -> pointer-based iterator and runtime increment
    {
      i = internal::random<Index>(0, A.rows() - 1);
      typename ColMatrixType::RowXpr Arow = A.row(i);
      VERIFY_IS_EQUAL(std::distance(Arow.begin(), Arow.end()), cols);
      std::sort(Arow.begin(), Arow.end());
      VERIFY(is_sorted(Arow.cbegin(), Arow.cend()));
      A.setRandom();
 
      std::sort(A.row(i).begin(), A.row(i).end());
      VERIFY(is_sorted(A.row(i).cbegin(), A.row(i).cend()));
      A.setRandom();
    }
 
    // with a generic iterator
    {
      Reshaped<RowMatrixType, RowMatrixType::SizeAtCompileTime, 1> B1 = B.reshaped();
      std::sort(B1.begin(), B1.end());
      VERIFY(is_sorted(B1.cbegin(), B1.cend()));
      B.setRandom();
 
      // assertion because nested expressions are different
      // std::sort(B.reshaped().begin(),B.reshaped().end());
      // VERIFY(is_sorted(B.reshaped().cbegin(),B.reshaped().cend()));
      // B.setRandom();
    }
  }
 
  // check with partial_sum
  {
    j = internal::random<Index>(0, A.cols() - 1);
    typename ColMatrixType::ColXpr Acol = A.col(j);
    std::partial_sum(Acol.begin(), Acol.end(), v.begin());
    VERIFY_IS_APPROX(v(seq(1, last)), v(seq(0, last - 1)) + Acol(seq(1, last)));
 
    // inplace
    std::partial_sum(Acol.begin(), Acol.end(), Acol.begin());
    VERIFY_IS_APPROX(v, Acol);
  }
 
  // stress random access as required by std::nth_element
  if (rows >= 3) {
    v.setRandom();
    VectorType v1 = v;
    std::sort(v1.begin(), v1.end());
    std::nth_element(v.begin(), v.begin() + rows / 2, v.end());
    VERIFY_IS_APPROX(v1(rows / 2), v(rows / 2));
 
    v.setRandom();
    v1 = v;
    std::sort(v1.begin() + rows / 2, v1.end());
    std::nth_element(v.begin() + rows / 2, v.begin() + rows / 4, v.end());
    VERIFY_IS_APPROX(v1(rows / 4), v(rows / 4));
  }
 
  // check rows/cols iterators with range-for loops
  {
    j = 0;
    for (auto c : A.colwise()) {
      VERIFY_IS_APPROX(c.sum(), A.col(j).sum());
      ++j;
    }
    j = 0;
    for (auto c : B.colwise()) {
      VERIFY_IS_APPROX(c.sum(), B.col(j).sum());
      ++j;
    }
 
    j = 0;
    for (auto c : B.colwise()) {
      i = 0;
      for (auto& x : c) {
        VERIFY_IS_EQUAL(x, B(i, j));
        x = A(i, j);
        ++i;
      }
      ++j;
    }
    VERIFY_IS_APPROX(A, B);
    B.setRandom();
 
    i = 0;
    for (auto r : A.rowwise()) {
      VERIFY_IS_APPROX(r.sum(), A.row(i).sum());
      ++i;
    }
    i = 0;
    for (auto r : B.rowwise()) {
      VERIFY_IS_APPROX(r.sum(), B.row(i).sum());
      ++i;
    }
  }
 
  // check rows/cols iterators with STL algorithms
  {
    RowVectorType row = RowVectorType::Random(cols);
    VectorType col = VectorType::Random(rows);
    // Prevent overflows for integer types.
    if (Eigen::NumTraits<Scalar>::IsInteger) {
      Scalar kMaxVal = Scalar(1000);
      row.array() = row.array() - kMaxVal * (row.array() / kMaxVal);
      col.array() = col.array() - kMaxVal * (col.array() / kMaxVal);
    }
    A.rowwise() = row;
    VERIFY(std::all_of(A.rowwise().begin(), A.rowwise().end(), [&row](typename ColMatrixType::RowXpr x) {
      return internal::isApprox(x.squaredNorm(), row.squaredNorm());
    }));
    VERIFY(std::all_of(A.rowwise().rbegin(), A.rowwise().rend(), [&row](typename ColMatrixType::RowXpr x) {
      return internal::isApprox(x.squaredNorm(), row.squaredNorm());
    }));
 
    A.colwise() = col;
    VERIFY(std::all_of(A.colwise().begin(), A.colwise().end(), [&col](typename ColMatrixType::ColXpr x) {
      return internal::isApprox(x.squaredNorm(), col.squaredNorm());
    }));
    VERIFY(std::all_of(A.colwise().rbegin(), A.colwise().rend(), [&col](typename ColMatrixType::ColXpr x) {
      return internal::isApprox(x.squaredNorm(), col.squaredNorm());
    }));
    VERIFY(std::all_of(A.colwise().cbegin(), A.colwise().cend(), [&col](typename ColMatrixType::ConstColXpr x) {
      return internal::isApprox(x.squaredNorm(), col.squaredNorm());
    }));
    VERIFY(std::all_of(A.colwise().crbegin(), A.colwise().crend(), [&col](typename ColMatrixType::ConstColXpr x) {
      return internal::isApprox(x.squaredNorm(), col.squaredNorm());
    }));
 
    i = internal::random<Index>(0, A.rows() - 1);
    A.setRandom();
    A.row(i).setZero();
    VERIFY_IS_EQUAL(
        std::find_if(A.rowwise().begin(), A.rowwise().end(),
                     [](typename ColMatrixType::RowXpr x) { return numext::is_exactly_zero(x.squaredNorm()); }) -
            A.rowwise().begin(),
        i);
    VERIFY_IS_EQUAL(
        std::find_if(A.rowwise().rbegin(), A.rowwise().rend(),
                     [](typename ColMatrixType::RowXpr x) { return numext::is_exactly_zero(x.squaredNorm()); }) -
            A.rowwise().rbegin(),
        (A.rows() - 1) - i);
 
    j = internal::random<Index>(0, A.cols() - 1);
    A.setRandom();
    A.col(j).setZero();
    VERIFY_IS_EQUAL(
        std::find_if(A.colwise().begin(), A.colwise().end(),
                     [](typename ColMatrixType::ColXpr x) { return numext::is_exactly_zero(x.squaredNorm()); }) -
            A.colwise().begin(),
        j);
    VERIFY_IS_EQUAL(
        std::find_if(A.colwise().rbegin(), A.colwise().rend(),
                     [](typename ColMatrixType::ColXpr x) { return numext::is_exactly_zero(x.squaredNorm()); }) -
            A.colwise().rbegin(),
        (A.cols() - 1) - j);
  }
 
  {
    using VecOp = VectorwiseOp<ArrayXXi, 0>;
    STATIC_CHECK((internal::is_same<VecOp::const_iterator, decltype(std::declval<const VecOp&>().cbegin())>::value));
    STATIC_CHECK((internal::is_same<VecOp::const_iterator, decltype(std::declval<const VecOp&>().cend())>::value));
    STATIC_CHECK(
        (internal::is_same<VecOp::const_iterator, decltype(std::cbegin(std::declval<const VecOp&>()))>::value));
    STATIC_CHECK((internal::is_same<VecOp::const_iterator, decltype(std::cend(std::declval<const VecOp&>()))>::value));
  }
}

References a, b, calibrate::c, check_begin_end_for_loop(), col(), cols, Eigen::PlainObjectBase< Derived >::cols(), Eigen::PlainObjectBase< Derived >::data(), Eigen::placeholders::end, i, is_default_constructible_and_assignable(), is_generic_randaccess_stl_iterator(), is_pointer_based_stl_iterator(), is_sorted(), j, Eigen::placeholders::last, make_reverse_iterator(), UniformPSDSelfTest::r, row(), rows, Eigen::PlainObjectBase< Derived >::rows(), Eigen::seq(), Eigen::PlainObjectBase< Derived >::setRandom(), Eigen::PlainObjectBase< Derived >::setZero(), STATIC_CHECK, swap(), tmp, v, v1(), Eigen::value, VERIFY, VERIFY_IS_APPROX, VERIFY_IS_EQUAL, VERIFY_IS_NOT_EQUAL, w, and plotDoE::x.