CECCO::TannerGraph< T > Struct Template Reference

Tanner graph of a parity-check matrix. More...

#include <graphs.hpp>

Classes
struct	BP_Workspace
	Workspace for sum-product (belief propagation) decoding. More...

Public Member Functions
	TannerGraph (size_t n)
	Construct a Tanner graph with n variable nodes and no checks.
void	add_edge (size_t check, uint32_t var_id, T value)
	Add a check-to-variable edge check --value--> var_id.
void	tikz_header (std::ostream &file) const
	Write TikZ style definitions.
void	tikz_picture (std::ostream &file, const BP_Workspace *ws) const
	Write one TikZ picture of the Tanner graph.
void	export_as_tikz (const std::string &filename, const BP_Workspace *ws) const
	Export a standalone TikZ fragment with workspace beliefs.
void	export_as_tikz (const std::string &filename) const
	Export a standalone TikZ fragment without workspace beliefs.

Public Attributes
size_t	n
	Number of variable nodes.
std::vector< std::vector< details::CheckEdge< T > > >	checks
	Incident edges by check node; checks[i] lists the variables in parity check i.

Detailed Description

template<FieldType T>
struct CECCO::TannerGraph< T >

Tanner graph of a parity-check matrix.

Template Parameters

T	Field type used for edge labels

Contains n variable nodes and one node per parity-check equation. An edge (check, variable, value) represents a nonzero parity-check coefficient. BP_Workspace provides sum-product decoding state.

Definition at line 938 of file graphs.hpp.

Constructor & Destructor Documentation

TannerGraph()

template<FieldType T>

CECCO::TannerGraph< T >::TannerGraph ( size_t n )

inlineexplicit

Construct a Tanner graph with n variable nodes and no checks.

Definition at line 940 of file graphs.hpp.

Member Function Documentation

add_edge()

template<FieldType T>

void CECCO::TannerGraph< T >::add_edge ( size_t check, uint32_t var_id, T value )

inline

Add a check-to-variable edge check --value--> var_id.

Parameters

check	Check-node index; checks are created on demand
var_id	Incident variable-node id
value	Parity-check coefficient carried by the edge

Exceptions

std::invalid_argument

if var_id is not a variable node of this graph

Definition at line 950 of file graphs.hpp.

export_as_tikz() [1/2]

template<FieldType T>

void CECCO::TannerGraph< T >::export_as_tikz ( const std::string & filename ) const

inline

Export a standalone TikZ fragment without workspace beliefs.

Parameters

filename

Output filename

Available only for finite fields of size at most 64.

Definition at line 1108 of file graphs.hpp.

export_as_tikz() [2/2]

template<FieldType T>

void CECCO::TannerGraph< T >::export_as_tikz ( const std::string & filename, const BP_Workspace * ws ) const

inline

Export a standalone TikZ fragment with workspace beliefs.

Parameters

filename	Output filename
ws	Optional decoding workspace; if non-null, posterior beliefs and decisions are shown

Available only for finite fields of size at most 64.

Definition at line 1091 of file graphs.hpp.

tikz_header()

template<FieldType T>

void CECCO::TannerGraph< T >::tikz_header ( std::ostream & file ) const

inline

Write TikZ style definitions.

Parameters

file	Output stream

Definition at line 1019 of file graphs.hpp.

tikz_picture()

template<FieldType T>

void CECCO::TannerGraph< T >::tikz_picture ( std::ostream & file, const BP_Workspace * ws ) const

inline

Write one TikZ picture of the Tanner graph.

Parameters

file	Output stream
ws	Optional decoding workspace; if non-null, posterior beliefs and decisions are shown

Available only for finite fields of size at most 64.

Definition at line 1031 of file graphs.hpp.

Member Data Documentation

checks

template<FieldType T>

std::vector<std::vector<details::CheckEdge<T> > > CECCO::TannerGraph< T >::checks

Incident edges by check node; checks[i] lists the variables in parity check i.

Definition at line 1117 of file graphs.hpp.

n

template<FieldType T>

size_t CECCO::TannerGraph< T >::n

Number of variable nodes.

Definition at line 1115 of file graphs.hpp.

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The documentation for this struct was generated from the following file:

• graphs.hpp