sparse_vector_ops.hpp File Reference

Operations on SparseVector: gather and scatter. More...

#include <initializer_list>
#include <vector>
#include <openpfc/core/backend_tags.hpp>
#include <openpfc/core/sparse_vector.hpp>

Include dependency graph for sparse_vector_ops.hpp:

This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Functions
template<typename BackendTag , typename T >
void	pfc::core::gather (SparseVector< BackendTag, T > &sparse_vector, const T *source, size_t source_size)
	Gather: Collect values from dense array into SparseVector.
template<typename T >
void	pfc::core::gather (core::SparseVector< backend::CpuTag, T > &sparse_vector, const std::vector< T > &source)
	Gather from std::vector (convenience overload for CPU)
template<typename T >
void	pfc::core::gather (core::SparseVector< backend::CpuTag, T > &sparse_vector, std::initializer_list< T > source)
	Gather from initializer list (convenience overload for CPU)
template<typename BackendTag , typename T >
void	pfc::core::scatter (const SparseVector< BackendTag, T > &sparse_vector, T *dest, size_t dest_size)
	Scatter: Write values from SparseVector into dense array.
template<typename T >
void	pfc::core::scatter (const core::SparseVector< backend::CpuTag, T > &sparse_vector, std::vector< T > &dest)
	Scatter to std::vector (convenience overload for CPU)

Detailed Description

Operations on SparseVector: gather and scatter.

Provides gather and scatter operations for SparseVector:

• gather: Collect values from dense array into SparseVector Direction: DenseArray → SparseVector
• scatter: Write values from SparseVector into dense array Direction: SparseVector → DenseArray

// Gather: Extract values at indices from source
std::vector<double> source = {1.0, 2.0, 3.0, 4.0, 5.0};
auto sparse = sparsevector::create<double>({0, 2, 4});
gather(sparse, source.data(), source.size());
// sparse.data() now contains {1.0, 3.0, 5.0}
 
// Scatter: Write values to destination at indices
std::vector<double> dest(5, 0.0);
scatter(sparse, dest.data(), dest.size());
// dest now contains {1.0, 0.0, 3.0, 0.0, 5.0}

See also

core/sparse_vector.hpp for SparseVector definition

Author

OpenPFC Development Team

Date

2025

Function Documentation

gather()

template<typename BackendTag , typename T >

void pfc::core::gather	(	SparseVector< BackendTag, T > &	sparse_vector,
		const T *	source,
		size_t	source_size
	)

Gather: Collect values from dense array into SparseVector.

Reads values from dense array at sparse_vector.indices and writes to sparse_vector.data.

Direction: DenseArray → SparseVector

Parameters

sparse_vector	SparseVector to fill
source	Pointer to dense array
source_size	Size of dense array

Here is the call graph for this function:

Here is the caller graph for this function:

scatter()

template<typename BackendTag , typename T >

void pfc::core::scatter	(	const SparseVector< BackendTag, T > &	sparse_vector,
		T *	dest,
		size_t	dest_size
	)

Scatter: Write values from SparseVector into dense array.

Writes values from sparse_vector.data into dense array at sparse_vector.indices.

Direction: SparseVector → DenseArray

Parameters

sparse_vector	SparseVector to read from
dest	Pointer to dense array
dest_size	Size of dense array

Here is the call graph for this function:

Here is the caller graph for this function: