How to modify some options for Matrix from existing type to create a new Matrix type in template pro-CodePudding

For example, assuming we have a matrix type T, can we create a new type that has only 1 cols like Matrix<..., ..., 1 ,...> and keep other options exactly the same in type T?

CodePudding user response：

In this particular case, this should be the simplest form:

using Matrix = Eigen::Matrix<...>; // your type
using Vector = typename Matrix::ColXpr::PlainObject;

CodePudding user response：

After some research I give following solution:

template<typename T1>
auto fun(const Eigen::MatrixBase<T1>& _X)
{
    using T = typename T1::PlainObject;
    using T2 = Eigen::Matrix<typename  T::Scalar,
        T::RowsAtCompileTime, T::ColsAtCompileTime,
        T::Options, T::MaxRowsAtCompileTime, T::MaxColsAtCompileTime>;

    if constexpr (std::is_same_v<T2, T>)
    {
        std::cout << "True" << std::endl;
    }
    return T();

}