固定大小的特征矩阵作为模板函数中的参数 [英] Fixed size Eigen matrix as parameters in template function

问题描述

我正在尝试编写一个使用矩阵大小上的模板的固定大小矩阵的函数.我已阅读 http://eigen.tuxfamily.org/dox/TopicFunctionTakingEigenTypes.html 但我无法使其完美运行.我无法在函数内部的固定大小矩阵上使用固定大小矩阵块操作. (TutorialBlockOperations.html> http://eigen.tuxfamily.org/dox/group_TutorialBlockOperations.html)

I am trying to write a function that takes fixed size matrix using template on the matrix size. I have read http://eigen.tuxfamily.org/dox/TopicFunctionTakingEigenTypes.html but I am not able to make it works perfectly. I could not use fixed size matrix block operations on the fixed size matrix inside my function. (TutorialBlockOperations.html">http://eigen.tuxfamily.org/dox/group_TutorialBlockOperations.html)

我试图通过两种方式来做到这一点，但是两者都没有用.

I tried to do it in two ways but both of them did not work.

这是函数定义A:

template <int N>
Matrix<double, 3, N> foo(const Matrix<double, 3, N>& v)
{
  Matrix<double, 3, N> ret;

  Vector3d a = v.leftCols<1>();  // error: expected primary-expression before ')' token

  return ret;
}

这是函数定义B:

template<typename Derived>
Eigen::MatrixBase<Derived> bar(const Eigen::MatrixBase<Derived>& v)
{
  EIGEN_STATIC_ASSERT_FIXED_SIZE(Derived);
  EIGEN_STATIC_ASSERT(Derived::RowsAtCompileTime == 3,
                  THIS_METHOD_IS_ONLY_FOR_MATRICES_OF_A_SPECIFIC_SIZE);

  Eigen::Matrix<double,
      Derived::RowsAtCompileTime,
      Derived::ColsAtCompileTime> ret;

  Vector3d a = v.leftCols<1>();  // error: expected primary-expression before ')' token

  return ret;
}

有什么想法吗?

推荐答案

版本B中的参数正确，但b！t不是应为Derived::PlainObject的返回类型.您还需要template disambiguate关键字来访问模板代码中的模板成员:

The argument in version B is correct, b!t not the return type which should be Derived::PlainObject. You also need the template disambiguate keyword to access template member within templated code:

template<typename Derived>
typename Derived::PlainObject bar(const Eigen::MatrixBase<Derived>& v)
{
  EIGEN_STATIC_ASSERT_FIXED_SIZE(Derived);
  EIGEN_STATIC_ASSERT(Derived::RowsAtCompileTime == 3,
                      THIS_METHOD_IS_ONLY_FOR_MATRICES_OF_A_SPECIFIC_SIZE);

  typename Derived::PlainObject ret;

  Vector3d a = v.template leftCols<1>();

  return ret;
}

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