Console and Library Functions

Topics covered in this chapter:

A large number of routines are available for both Console and Library users of the FICO Xpress Optimizer, ranging from simple routines for the input and solution of problems from matrix files to sophisticated callback functions and greater control over the solution process. Of these, the core functionality is available to both sets of users and comprises the 'Console Mode'. Library users additionally have access to a set of more 'advanced' functions, which extend the functionality provided by the Console Mode, providing more control over their program's interaction with the Optimizer and catering for more complicated problem development.

Console Mode Functions

With both the Console and Advanced Mode functions described side-by-side in this chapter, library users can use this as a quick reference for the full capabilities of the Optimizer library. For users of Console Optimizer, only the following functions will be of relevance:

Command	Description
CHECKCONVEXITY	Convexity checker. [ Linear Algebra, Quadratic]
EXIT	Terminate the Console Optimizer. [ Misc]
HELP	Quick reference help for the Optimizer console. [ Misc]
IIS	Console IIS command. [ Infeasibility]
PRINTSOL	Write the current solution to screen. [ Solution]
QUIT	Terminate the Console Optimizer. [ Misc]
STOP	Terminate the Console Optimizer. [ Misc]
TUNE	Console Tuner command. [ Tuner]
SETARCHCONSISTENCY	Sets whether to force the same execution path on various CPU architecture extensions, in particular (pre-)AVX and AVX2. [ Global Environment]
BASISSTABILITY	Calculates various measures for the stability of the current basis, including the basis condition number. [ Linear Algebra, LP]
CHGOBJSENSE	Changes the problem's objective function sense to minimize or maximize. [ Problem Modification]
DUMPCONTROLS	Displays the list of controls and their current value for those controls that have been set to a non default value. [ Controls and Attributes]
FIXMIPENTITIES	Fixes all the MIP entities to the values of the last found MIP solution. [ MIP Entities, Problem Modification]
LPOPTIMIZE	This function begins a search for the optimal continuous (LP) solution. [ LP, Solution Process]
MIPOPTIMIZE	This function begins a tree search for the optimal MIP solution. [ MIP Entities, Solution Process]
OPTIMIZE	This function begins a search for the optimal solution of the problem. [ Solution Process]
POSTSOLVE	Postsolve the current matrix when it is in a presolved state. [ Presolve, Solution Process]
READBASIS	Instructs the Optimizer to read in a previously saved basis from a file. [ File IO, LP]
READBINSOL	Reads a solution from a binary solution file. [ File IO, Solution]
READDIRS	Reads a directives file to help direct the tree search. [ Branching, File IO]
READPROB	Reads an (X)MPS or LP format matrix from file. [ File IO, Problem Creation]
READSLXSOL	Reads an ASCII solution file .slx created by the XPRSwriteslxsol function. [ File IO, Solution]
REPAIRINFEAS	An extended version of XPRSrepairweightedinfeas that allows for bounding the level of relaxation allowed. [ Infeasibility]
RESTORE	Restores the Optimizer's data structures from a file created by XPRSsave (SAVE). [ File IO, Save Restore]
SAVE	Saves the current data structures to file and terminates the run [ File IO, Save Restore]
SCALE	Re-scales the current matrix. [ Numerics]
SETDEFAULTCONTROL	Sets a single control to its default value. [ Controls and Attributes]
SETDEFAULTS	Sets all controls to their default values. [ Controls and Attributes]
SETLOGFILE	This directs all Optimizer output to a log file. [ File IO, Logging]
SETPROBNAME	Sets the current default problem name. [ Problem Information]
WRITEBASIS	Writes the current basis to a file for later input into the Optimizer. [ File IO, LP]
WRITEBINSOL	Writes the current MIP or LP solution to a binary solution file for later input into the Optimizer. [ File IO, Solution]
WRITEDIRS	Writes the tree search directives from the current problem to a directives file. [ Branching, File IO]
WRITEPROB	Writes the current problem to an MPS or LP file. [ File IO]
WRITEPRTSOL	Writes the current solution to a fixed format ASCII file, problem_name .prt. [ File IO, Solution]
WRITESLXSOL	Creates an ASCII solution file (.slx) using a similar format to MPS files. These files can be read back into the Optimizer using the XPRSreadslxsol function. [ File IO, Solution]
WRITESOL	Writes the current solution to a CSV format ASCII file, problem_name.asc (and .hdr). [ File IO, Solution]

For a list of functions by task, refer to Function Quick Reference.

Layout for Function Descriptions

All functions mentioned in this chapter are described under the following set of headings:

Function Name

The description of each routine starts on a new page. The library name for a function is on the left and the Console Optimizer command name, if one exists, is on the right.

Purpose

A short description of the routine and its purpose begins the information section.

Synopsis

A synopsis of the syntax for usage of the routine is provided. "Optional" arguments and flags may be specified as NULL if not required. Where this possibility exists, it will be described alongside the argument, or in the Further Information at the end of the routine's description. If the function is available in the Console, the library syntax is described first, followed by the Console Optimizer syntax.

Arguments

A list of arguments to the routine with a description of possible values for them follows.

Error Values

Optimizer return codes are described in Chapter Return Codes and Error Messages.

Likely error values returned by this for each function are listed in the Error Values section. A description of the error may be obtained using the XPRSgetlasterror function. If no attention need be drawn to particular error values, this section will be omitted.

Associated Controls

Controls which affect a given routine are listed next, separated into lists by type. The control name given here should have XPRS_ prefixed by library users, in a similar way to the XPRSgetintattrib example in the Error Values section above. Console Xpress users should use the controls without this prefix, as described in FICO Xpress Getting Started manual. These controls must be set before the routine is called if they are to have any effect.

Examples

One or two examples are provided which explain certain aspects of the routine's use.

Further Information

Additional information not contained elsewhere in the routine's description is provided at the end.

Contents

Index

Glossary

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