regina::LPCol< LPConstraint > Struct Template Reference

Used by LPInitialTableaux<LPConstraint> to store a single column of the adjusted matching equation matrix in sparse form. More...

#include <enumerate/treelp.h>

Public Member Functions
	LPCol ()
	Initialises an empty column. More...
	LPCol (const LPCol &)=default
	Creates a new copy of the given column. More...
	LPCol (LPCol &&)=default
	Moves the contents of the given column into this new column. More...
LPCol &	operator= (const LPCol &)=default
	Sets this to be a copy of the given column. More...
LPCol &	operator= (LPCol &&)=default
	Moves the contents of the given column into this column. More...
void	push (unsigned row, int val)
	Adds the given entry in the given row to this column. More...

Public Attributes
unsigned	nPlus
	The total number of +1 entries in this column. More...
unsigned	plus [4]
	The rows containing these +1 entries, in any order. More...
unsigned	nMinus
	The total number of -1 entries in this column. More...
unsigned	minus [4]
	The rows containing these -1 entries, in any order. More...
std::array< typename LPConstraint::Coefficient, LPConstraint::nConstraints >	extra
	The coefficients for this column that appear in each extra linear constraint defined by the LPConstraint class. More...

Detailed Description

template<class LPConstraint>
struct regina::LPCol< LPConstraint >

Used by LPInitialTableaux<LPConstraint> to store a single column of the adjusted matching equation matrix in sparse form.

See the LPInitialTableaux class notes for details on what the "adjusted matching equation matrix" means.

Specifically, an LPCol object stores the location of each +1 entry, and the location of each -1 entry. If some entry in the matrix is greater than +1 or less than -1, we represent it using multiple +1 or -1 entries in the same matrix location.

For any additional rows that represent extra linear constraints described by the LPConstraint class, an LPCol object stores the coefficients for those rows explicitly. The number of such rows is assumed to be very small (at the time of writing, this is no larger than 2 for all of Regina's constraint classes).

These column objects have full value semantics. Assuming the number of rows from any extra linear constraints is very small (as noted above), these column objects are cheap to move, cheap to copy, and cheap to swap via std::swap().

Warning

End users should not use this class at all. It was designed purely for use as internal storage for LPInitialTableaux, and at some point in the future this class will most likely become private to LPInitialTableaux.

Python

Not present, since LPCol is only designed to be used as part of the internal data storage for LPInitialTableaux.

Warning

The API for this class has not yet been finalised. This means that the class interface may change in new versions of Regina, without maintaining backward compatibility. If you use this class directly in your own code, please watch the detailed changelogs upon new releases to see if you need to make changes to your code.

Constructor & Destructor Documentation

LPCol() [1/3]

template<class LPConstraint >

regina::LPCol< LPConstraint >::LPCol

inline

Initialises an empty column.

LPCol() [2/3]

template<class LPConstraint >

regina::LPCol< LPConstraint >::LPCol ( const LPCol< LPConstraint > &  )

default

Creates a new copy of the given column.

LPCol() [3/3]

template<class LPConstraint >

regina::LPCol< LPConstraint >::LPCol ( LPCol< LPConstraint > &&  )

default

Moves the contents of the given column into this new column.

This move operation is not marked noexcept, since this depends upon the underlying LPConstraint class.

After this operation, the given column will no longer be usable.

Member Function Documentation

operator=() [1/2]

template<class LPConstraint >

LPCol & regina::LPCol< LPConstraint >::operator= ( const LPCol< LPConstraint > &  )

default

Sets this to be a copy of the given column.

Returns

a reference to this column.

operator=() [2/2]

template<class LPConstraint >

LPCol & regina::LPCol< LPConstraint >::operator= ( LPCol< LPConstraint > &&  )

default

Moves the contents of the given column into this column.

This move operation is not marked noexcept, since this depends upon the underlying LPConstraint class.

After this operation, the given column will no longer be usable.

Returns

a reference to this column.

push()

template<class LPConstraint >

void regina::LPCol< LPConstraint >::push ( unsigned  row, int  val  )

inline

Adds the given entry in the given row to this column.

Precondition

No entry in the given row has been added to this column yet.

The sum of absolute values of all entries in this column must never exceed 4.

Parameters

row	the row containing the given value.
val	the value at this location in the matrix.

Member Data Documentation

extra

template<class LPConstraint >

std::array<typename LPConstraint::Coefficient, LPConstraint::nConstraints> regina::LPCol< LPConstraint >::extra

The coefficients for this column that appear in each extra linear constraint defined by the LPConstraint class.

minus

template<class LPConstraint >

unsigned regina::LPCol< LPConstraint >::minus[4]

The rows containing these -1 entries, in any order.

The same row may appear in this list more than once (indicating a -2, -3 or -4 entry in the matrix).

nMinus

template<class LPConstraint >

unsigned regina::LPCol< LPConstraint >::nMinus

The total number of -1 entries in this column.

nPlus

template<class LPConstraint >

unsigned regina::LPCol< LPConstraint >::nPlus

The total number of +1 entries in this column.

plus

template<class LPConstraint >

unsigned regina::LPCol< LPConstraint >::plus[4]

The rows containing these +1 entries, in any order.

The same row may appear in this list more than once (indicating a +2, +3 or +4 entry in the matrix).

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

• enumerate/treeconstraint.h
• enumerate/treelp.h