Module sparse 

Sparse matrix structures (CSR format)

This module provides Compressed Sparse Row (CSR) format for efficient storage and matrix-vector operations with sparse matrices.

CSR format stores:

• values: Non-zero entries in row-major order
• col_indices: Column index for each value
• row_ptrs: Index into values/col_indices where each row starts

For BEM, the near-field matrix is sparse (only nearby element interactions), while far-field is handled via FMM factorization.

Structs

BlockedCsr

Blocked CSR format for hierarchical matrices

CsrBuilder

Builder for constructing CSR matrices row by row

CsrMatrix

Compressed Sparse Row (CSR) matrix format