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Problem Attributes

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During the optimization process, various properties of the problem being solved are stored and made available to users of the Xpress-SLP Libraries in the form of problem attributes. These can be accessed in much the same manner as the controls. Examples of problem attributes include the sizes of arrays, for which library users may need to allocate space before the arrays themselves are retrieved. A full list of the attributes available and their types may be found in this chapter.

Library users are provided with the following functions for obtaining the values of attributes:

XSLPgetintattrib	XSLPgetdblattrib
XSLPgetptrattrib	XSLPgetstrattrib

The attributes listed in this chapter are all prefixed with XSLP_. It is possible to use the above functions with attributes for the Xpress Optimizer (attributes prefixed with XPRS_). For details of the Optimizer attributes, see the Optimizer manual.

Example of the usage of the functions:

XSLPgetintattrib(Prob, XSLP_ITER, &nIter);
printf("The number of SLP iterations is %d\n", nIter);
XSLPgetdblattrib(Prob, XSLP_ERRORCOSTS, &Errors);
printf("and the total error cost is %lg\n", Errors);

The following is a list of all the Xpress-SLP attributes:

XSLP_COEFFICIENTS	Number of nonlinear coefficients
XSLP_CURRENTDELTACOST	Current value of penalty cost multiplier for penalty delta vectors
XSLP_CURRENTERRORCOST	Current value of penalty cost multiplier for penalty error vectors
XSLP_CVS	Number of character variables
XSLP_DELTAS	Number of delta vectors created during augmentation
XSLP_ECFCOUNT	Number of infeasible constraints found at the point of linearization
XSLP_EQUALSCOLUMN	Index of the reserved "=" column
XSLP_ERRORCOSTS	Total penalty costs in the solution
XSLP_GLOBALFUNCOBJECT	The user-defined global function object
XSLP_IFS	Number of internal functions
XSLP_IMPLICITVARIABLES	Number of SLP variables appearing only in coefficients
XSLP_INTERNALFUNCCALLS	Number of calls made to internal functions
XSLP_ITER	SLP iteration count
XSLP_MINORVERSION	Xpress-SLP minor version number
XSLP_MINUSPENALTYERRORS	Number of negative penalty error vectors
XSLP_MIPITER	Total number of SLP iterations in MISLP
XSLP_MIPNODES	Number of nodes explored in MISLP
XSLP_MIPPROBLEM	The underlying Optimizer MIP problem
XSLP_NONLINEARCONSTRAINTS	Number of nonlinear constraints in the problem
XSLP_OBJSENSE	Objective function sense
XSLP_OBJVAL	Objective function value excluding any penalty costs
XSLP_PENALTYDELTACOLUMN	Index of column costing the penalty delta row
XSLP_PENALTYDELTAROW	Index of equality row holding the penalties for delta vectors
XSLP_PENALTYDELTAS	Number of penalty delta vectors
XSLP_PENALTYDELTATOTAL	Total activity of penalty delta vectors
XSLP_PENALTYDELTAVALUE	Total penalty cost attributed to penalty delta vectors
XSLP_PENALTYERRORCOLUMN	Index of column costing the penalty error row
XSLP_PENALTYERRORROW	Index of equality row holding the penalties for penalty error vectors
XSLP_PENALTYERRORS	Number of penalty error vectors
XSLP_PENALTYERRORTOTAL	Total activity of penalty error vectors
XSLP_PENALTYERRORVALUE	Total penalty cost attributed to penalty error vectors
XSLP_PLUSPENALTYERRORS	Number of positive penalty error vectors
XSLP_PRESOLVEPASSES	Number of passes made by the SLP nonlinear presolve procedure
XSLP_SBXCONVERGED	Number of step-bounded variables converged only on extended criteria
XSLP_STATUS	Bitmap holding the problem convergence status
XSLP_TOLSETS	Number of tolerance sets
XSLP_UCCONSTRAINEDCOUNT	Number of unconverged variables with coefficients in constraining rows
XSLP_UFINSTANCES	Number of user function instances
XSLP_UFS	Number of user functions
XSLP_UNCONVERGED	Number of unconverged values
XSLP_UNIQUEPREFIX	Unique prefix for generated names
XSLP_USEDERIVATIVES	Indicates whether numeric or analytic derivatives were used to create the linear approximations and solve the problem
XSLP_USERFUNCCALLS	Number of calls made to user functions
XSLP_VALIDATIONINDEX_A	Absolute validation index
XSLP_VALIDATIONINDEX_R	Relative validation index
XSLP_VARIABLES	Number of SLP variables
XSLP_VERSION	Xpress-SLP major version number
XSLP_VERSIONDATE	Date of creation of Xpress-SLP
XSLP_XPRSPROBLEM	The underlying Optimizer problem
XSLP_XSLPPROBLEM	The Xpress-SLP problem
XSLP_XVS	Number of extended variable arrays

Double problem attributes

Integer problem attributes

Reference (pointer) problem attributes

The reference attributes are void pointers whose size (32 or 64 bit) depends on the platform.

String problem attributes

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