如何从特征矩阵列/行中获取特征向量？

Question

The thing I want to do is this:我想做的是这样的：

MatrixXd M;
// Whatever assigned to `X`
VectorXd V = M(1);

Eigen does not support this.本征不支持这一点。 Is there a way to retrieve an Eigen vector from an Eigen matrix?有没有办法从特征矩阵中检索特征向量？

Answer 1

Eigen Slicing and Indexing is of much use here.特征切片和索引在这里很有用。

To retrieve an i -th row vector:要检索第i行向量：

VectorXd V = M(i, all);

To retrieve an i -th column vector:要检索第i个列向量：

VectorXd V = M(all, i);