# doubleton_action Class Reference

Solve ax+by=c for y and substitute y out of the problem. More...

`#include <CoinPresolveDoubleton.hpp>`

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List of all members.

## Classes
struct | action
## Public Member Functions
const char * | name () const
| A name for debug printing.
void | postsolve (CoinPostsolveMatrix *prob) const
| Apply the postsolve transformation for this particular presolve action.
virtual | ~doubleton_action ()
## Static Public Member Functions
static const CoinPresolveAction * | presolve (CoinPresolveMatrix *, const CoinPresolveAction *next)
## Public Attributes
const int | nactions_
const action *const | actions_
## Private Member Functions
| doubleton_action (int nactions, const action *actions, const CoinPresolveAction *next)

## Detailed Description

Solve ax+by=c for y and substitute y out of the problem.

This moves the bounds information for y onto x, making y free and allowing us to substitute it away.

    	   a x + b y = c
    	   l1 <= x <= u1
    	   l2 <= y <= u2	==>

    	   l2 <= (c - a x) / b <= u2
    	   b/-a > 0 ==> (b l2 - c) / -a <= x <= (b u2 - c) / -a
    	   b/-a < 0 ==> (b u2 - c) / -a <= x <= (b l2 - c) / -a

Definition at line 26 of file CoinPresolveDoubleton.hpp.

## Constructor & Destructor Documentation

doubleton_action::doubleton_action | ( | int | nactions,
|  | const action * | actions,
|  | const CoinPresolveAction * | next |
| ) |  |  | `[inline, private]`

Definition at line 54 of file CoinPresolveDoubleton.hpp.

virtual doubleton_action::~doubleton_action | ( |  | ) | `[virtual]`

## Member Function Documentation

const char* doubleton_action::name | ( |  | ) | const`[inline, virtual]`

A name for debug printing.

It is expected that the name is not stored in the transform itself.

Implements CoinPresolveAction.

Definition at line 62 of file CoinPresolveDoubleton.hpp.

static const CoinPresolveAction* doubleton_action::presolve | ( | CoinPresolveMatrix * | ,
|  | const CoinPresolveAction * | next |
| ) |  |  | `[static]`

void doubleton_action::postsolve | ( | CoinPostsolveMatrix * | prob | ) | const`[virtual]`

Apply the postsolve transformation for this particular presolve action.

Implements CoinPresolveAction.

## Member Data Documentation

const int doubleton_action::nactions_

Definition at line 50 of file CoinPresolveDoubleton.hpp.

const action* const doubleton_action::actions_

Definition at line 51 of file CoinPresolveDoubleton.hpp.

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

- /home/coin/svn-release/Alps-1.5.2/CoinUtils/src/CoinPresolveDoubleton.hpp