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# Presolve Debug Functions

## Functions
void | CoinPresolveMatrix::presolve_no_dups (const CoinPresolveMatrix *preObj, bool doCol=true, bool doRow=true)
| Check column-major and/or row-major matrices for duplicate entries in the major vectors.
void | CoinPresolveMatrix::presolve_links_ok (const CoinPresolveMatrix *preObj, bool doCol=true, bool doRow=false)
| Check the links which track storage order for major vectors in the bulk storage area.
void | CoinPresolveMatrix::presolve_no_zeros (const CoinPresolveMatrix *preObj, bool doCol=true, bool doRow=true)
| Check for explicit zeros in the column- and/or row-major matrices.
void | CoinPresolveMatrix::presolve_consistent (const CoinPresolveMatrix *preObj, bool chkvals=true)
| Checks for equivalence of the column- and row-major matrices.
void | CoinPostsolveMatrix::presolve_check_threads (const CoinPostsolveMatrix *obj)
| Checks that column threads agree with column lengths.
void | CoinPostsolveMatrix::presolve_check_free_list (const CoinPostsolveMatrix *obj, bool chkElemCnt=false)
| Checks the free list.
void | CoinPostsolveMatrix::presolve_check_reduced_costs (const CoinPostsolveMatrix *obj)
| Check stored reduced costs for accuracy and consistency with variable status.
void | CoinPostsolveMatrix::presolve_check_duals (const CoinPostsolveMatrix *postObj)
| Check the dual variables for consistency with row activity.
void | CoinPresolveMatrix::presolve_check_sol (const CoinPresolveMatrix *preObj, int chkColSol=2, int chkRowAct=1, int chkStatus=1)
| Check primal solution and architectural variable status.
void | CoinPostsolveMatrix::presolve_check_sol (const CoinPostsolveMatrix *postObj, int chkColSol=2, int chkRowAct=2, int chkStatus=1)
| Check primal solution and architectural variable status.
void | CoinPostsolveMatrix::presolve_check_nbasic (const CoinPostsolveMatrix *postObj)
| Check for the proper number of basic variables.

## Detailed Description

These functions implement consistency checks on data structures involved in presolve and postsolve and on the components of the lp solution.

To use these functions, include CoinPresolvePsdebug.hpp in your file and define the compile-time constants PRESOLVE_SUMMARY, PRESOLVE_DEBUG, and PRESOLVE_CONSISTENCY (either in individual files or in Coin/Makefile). A value is needed (i.e., PRESOLVE_DEBUG=1) but not at present used to control debug level. Be sure that the definition occurs before any CoinPresolve*.hpp file is processed.

## Function Documentation

void presolve_no_dups | ( | const CoinPresolveMatrix * | preObj,
|  | bool | doCol = `true`,
|  | bool | doRow = `true` |
| ) |  |  | `[related, inherited]`

Check column-major and/or row-major matrices for duplicate entries in the major vectors.

By default, scans both the column- and row-major matrices. Set doCol (doRow) to false to suppress one or the other.

void presolve_links_ok | ( | const CoinPresolveMatrix * | preObj,
|  | bool | doCol = `true`,
|  | bool | doRow = `false` |
| ) |  |  | `[related, inherited]`

Check the links which track storage order for major vectors in the bulk storage area.

By default, scans only the column-major matrix. Set doCol = false to suppress the scan. Set doRow = false to scan the row-major links. But be warned, the row-major links are not maintained with the same zeal as the column-major links.

void presolve_no_zeros | ( | const CoinPresolveMatrix * | preObj,
|  | bool | doCol = `true`,
|  | bool | doRow = `true` |
| ) |  |  | `[related, inherited]`

Check for explicit zeros in the column- and/or row-major matrices.

By default, scans both the column- and row-major matrices. Set doCol (doRow) to false to suppress one or the other.

void presolve_consistent | ( | const CoinPresolveMatrix * | preObj,
|  | bool | chkvals = `true` |
| ) |  |  | `[related, inherited]`

Checks for equivalence of the column- and row-major matrices.

Normally the routine will test for coefficient presence and value. Set `chkvals` to false to suppress the check for equal value.

void presolve_check_threads | ( | const CoinPostsolveMatrix * | obj | ) | `[related, inherited]`

Checks that column threads agree with column lengths.

void presolve_check_free_list | ( | const CoinPostsolveMatrix * | obj,
|  | bool | chkElemCnt = `false` |
| ) |  |  | `[related, inherited]`

Checks the free list.

Scans the thread of free locations in the bulk store and checks that all entries are reasonable (0 <= index < bulk0_). If chkElemCnt is true, it Also checks that the total number of entries in the matrix plus the locations on the free list total to the size of the bulk store. Postsolve routines do not maintain an accurate element count, but this is useful for checking a newly constructed postsolve matrix.

void presolve_check_reduced_costs | ( | const CoinPostsolveMatrix * | obj | ) | `[related, inherited]`

Check stored reduced costs for accuracy and consistency with variable status.

The routine will check the value of the reduced costs for architectural variables (CoinPrePostsolveMatrix::rcosts_). It performs an accuracy check by recalculating the reduced cost from scratch. It will also check the value for consistency with the status information in CoinPrePostsolveMatrix::colstat_.

void presolve_check_duals | ( | const CoinPostsolveMatrix * | postObj | ) | `[related, inherited]`

Check the dual variables for consistency with row activity.

The routine checks that the value of the dual variable is consistent with the state of the constraint (loose, tight at lower bound, or tight at upper bound).

void presolve_check_sol | ( | const CoinPresolveMatrix * | preObj,
|  | int | chkColSol = `2`,
|  | int | chkRowAct = `1`,
|  | int | chkStatus = `1` |
| ) |  |  | `[related, inherited]`

Check primal solution and architectural variable status.

The architectural variables can be checked for bogus values, feasibility, and valid status. The row activity is checked for bogus values, accuracy, and feasibility. By default, row activity is not checked (presolve is sloppy about maintaining it). See the definitions in CoinPresolvePsdebug.cpp for more information.

void presolve_check_sol | ( | const CoinPostsolveMatrix * | postObj,
|  | int | chkColSol = `2`,
|  | int | chkRowAct = `2`,
|  | int | chkStatus = `1` |
| ) |  |  | `[related, inherited]`

Check primal solution and architectural variable status.

The architectural variables can be checked for bogus values, feasibility, and valid status. The row activity is checked for bogus values, accuracy, and feasibility. See the definitions in CoinPresolvePsdebug.cpp for more information.

void presolve_check_nbasic | ( | const CoinPostsolveMatrix * | postObj | ) | `[related, inherited]`

Check for the proper number of basic variables.