Block operations on Sparse Matrices- Eigen Toolbox- C++

问题:

Block operations for sparse matrices - Eigen Toolbox - C++    #include "Eigen/Dense" #include "Eigen/Sparse" #include  using namespace std; using namespace Eigen;      int main()     {     MatrixXd silly(6, 3);     silly  sparse_silly,temp;         sparse_silly= Eigen::SparseMatrix(6, 3);         temp = Eigen::SparseMatrix(6, 3);         sparse_silly = silly.sparseView();          std::cout 

In the above code, the block operations for sparse matrices are not working using Eigen toolbox. I want a assign a block from a sparse_silly to a block in temp matrix. The output printed is zero for the temp matrix.Can anyone help me if i missed something conceptually. The recent documentation says block operations are availble for sparse matrices.

回答1:

Blocks of sparse matrices in Eigen are not all writable. Certain ones are (e.g. .col(Index) in a column major matrix) but the generic .block(Index, Index, Index, Index) is not. The documentation is quite confusing on that matter, but if you look closely, all the examples are with dense matrices and not sparse ones. The col() documentation uses a dense matrix example as well, but if you try it, you'll see that it works.

文章来源: Block operations on Sparse Matrices- Eigen Toolbox- C++