c++ - Eigen 3.3.4 : What is the way to create Map to 2d Block?

Question

假设我有以下代码:

MatrixXd v(10, 10);
auto block = v.block(5, 0, 5, 2);  // a block xpr to v
// view the block as vector
// in Eigen 3.4 it would be block.reshaped()
// but for Eigen 3.3, the following does not work:
Map<VectorXd>(block.data(), 10) = VectorXd::LinSpaced(10, 0, 1.);
// or the other way around, which errors on the constness
block = Map<MatrixXd>(VectorXd::LinSpaced(10, 0., 1.).eval().data(), 5, 2);

我的问题是，是否有使用 Eigen 3.3 实现此目的的好方法？

Answer 1

临时的“另一种方式”就可以了，你所要做的就是使用 Map<const MatrixXd> 来尊重常量。或静态方法 MatrixXd::Map :

block = Map<const MatrixXd>(VectorXd::LinSpaced(10, 0., 1.).eval().data(), 5, 2);
block = MatrixXd::Map(VectorXd::LinSpaced(10, 0., 1.).eval().data(), 5, 2);