tk::CSR class
#include <src/LinearSolver/CSR.hpp>

Compressed sparse row (CSR) storage for a sparse matrix.

Constructors, destructors, conversion operators

CSR(std::size_t nc, const std::pair<std::vector<std::size_t>, std::vector<std::size_t>>& psup) explicit: Constructor: Create a CSR symmetric matrix with ncomp scalar components, storing only the upper triangular part.
CSR() defaulted explicit: Empty constructor for Charm++.

Public functions

auto operator()(std::size_t row, std::size_t col, std::size_t pos = 0) const -> const real&: Return const reference to sparse matrix entry at a position.
auto operator()(std::size_t row, std::size_t col, std::size_t pos = 0) -> real&
void dirichlet(std::size_t i, tk::real val, std::vector<tk::real>& b, const std::vector<std::size_t>& gid = {}, const std::unordered_map<int, std::unordered_set<std::size_t>>& nodecommap = {}, std::size_t pos = 0): Set Dirichlet boundary condition at a node.
void mult(const std::vector<real>& x, std::vector<real>& r) const: Multiply CSR matrix with vector from the right: r = A * x.
void zero(): Zero matrix values.
auto rsize() const -> std::size_t: Access real size of matrix.
auto Ncomp() const -> std::size_t: Access the number of scalar components per non-zero matrix entry.
auto write_stored(std::ostream& os) const -> std::ostream&: Write out CSR as stored.
auto write_structure(std::ostream& os) const -> std::ostream&: Write out CSR nonzero structure.
auto write_contribute(std::ostream& os) const -> std::ostream&: Write out CSR contribute structure.
auto write_matrix(std::ostream& os) const -> std::ostream&: Write out CSR as a real matrix.
auto write_matlab(std::ostream& os) const -> std::ostream&: Write out CSR in Matlab/Octave format.

Pack/unpack (Charm++ serialization) routines

void pup(PUP::er& p): Pack/Unpack serialize member function.
void operator|(PUP::er& p, CSR& c): Pack/Unpack serialize operator|.

Function documentation

tk::CSR::CSR(std::size_t nc, const std::pair<std::vector<std::size_t>, std::vector<std::size_t>>& psup) explicit

Constructor: Create a CSR symmetric matrix with ncomp scalar components, storing only the upper triangular part.

Parameters
nc in	Number of scalar components (degrees of freedom)
psup in	Points surrounding points of mesh graph, see tk::genPsup

const real& tk::CSR::operator()(std::size_t row, std::size_t col, std::size_t pos = 0) const

Return const reference to sparse matrix entry at a position.

Parameters
row in	Block row
col in	Block column
pos in	Position in block
Returns	Const reference to matrix entry at position specified

real& tk::CSR::operator()(std::size_t row, std::size_t col, std::size_t pos = 0)

Return non-const reference to sparse matrix entry at a position

void tk::CSR::dirichlet(std::size_t i, tk::real val, std::vector<tk::real>& b, const std::vector<std::size_t>& gid = {}, const std::unordered_map<int, std::unordered_set<std::size_t>>& nodecommap = {}, std::size_t pos = 0)

Set Dirichlet boundary condition at a node.

Parameters
i in	Local id at which to set Dirichlet BC
val in	Value of Dirichlet BC
b in/out	RHS to modify as a result of setting the Dirichlet BC
gid in	Local->global node id map
nodecommap in	Node communication map with global node ids
pos in	Position in block

In parallel there can be multiple contributions to a single node on the mesh, and correspondingly, a single matrix row can be partially represented on multiple partitions. Setting a Dirichlet BC entails zeroing out the row of the matrix and putting 1/N into the diagonal entry, where N is the number of partitions that contribute to the mesh node (matrix row). As a result, when the matrix participates in a matrix-vector product, where the partial contributions across all partitions are aggregated, the diagonal will contain 1 after the sum across partitions.

void tk::CSR::mult(const std::vector<real>& x, std::vector<real>& r) const

Multiply CSR matrix with vector from the right: r = A * x.

Parameters
x in	Vector to multiply matrix with from the right
r in	Result vector of product r = A * x

std::ostream& tk::CSR::write_stored(std::ostream& os) const

Write out CSR as stored.

Parameters
os in/out	Output stream to write to
Returns	Updated output stream

std::ostream& tk::CSR::write_structure(std::ostream& os) const

Write out CSR nonzero structure.

Parameters
os in/out	Output stream to write to
Returns	Updated output stream

std::ostream& tk::CSR::write_matrix(std::ostream& os) const

Write out CSR as a real matrix.

Parameters
os in/out	Output stream to write to
Returns	Updated output stream

std::ostream& tk::CSR::write_matlab(std::ostream& os) const

Write out CSR in Matlab/Octave format.

Parameters
os in/out	Output stream to write to
Returns	Updated output stream

void tk::CSR::pup(PUP::er& p)

Pack/Unpack serialize member function.

Parameters
p in/out	Charm++'s PUP::er serializer object reference

void tk::CSR::operator|(PUP::er& p, CSR& c)

Pack/Unpack serialize operator|.

Parameters
p in/out	Charm++'s PUP::er serializer object reference
c in/out	CSR object reference