Control Parameters
Various controls exist within Xpress-SLP to govern the solution procedure and the form of the output. Some of these take integer values and act as switches between various types of behavior. Many are tolerances on values related to the convergence criteria; these are all double precision. There are also a few controls which are character strings, setting names for structures. Any of these may be altered by the user to enhance performance of the SLP algorithm. In most cases, the default values provided have been found to work well in practice over a range of problems and caution should be exercised if they are changed.
Users of the Xpress-SLP function library are provided with the following set of functions for setting and obtaining control values:
XSLPgetintcontrol XSLPgetdblcontrol XSLPgetstrcontrol XSLPsetintcontrol XSLPsetdblcontrol XSLPsetstrcontrol All the controls as listed in this chapter are prefixed with XSLP_. It is possible to use the above functions with control parameters for the Xpress Optimizer (controls prefixed with XPRS_). For details of the Optimizer controls, see the Optimizer manual.
Example of the usage of the functions:
XSLPgetintcontrol(Prob, XSLP_PRESOLVE, &presolve); printf("The value of PRESOLVE was %d\n", presolve); XSLPsetintcontrol(Prob, XSLP_PRESOLVE, 1-presolve); printf("The value of PRESOLVE is now %d\n", 1-presolve);The following is a list of all the Xpress-SLP controls:
XSLP_ALGORITHM XSLP_ATOL_A XSLP_ATOL_R XSLP_AUGMENTATION XSLP_AUTOSAVE XSLP_BARLIMIT XSLP_CASCADE XSLP_CASCADENLIMIT XSLP_CASCADETOL_PA XSLP_CASCADETOL_PR XSLP_CONTROL XSLP_CTOL XSLP_CVNAME XSLP_DAMP XSLP_DAMPEXPAND XSLP_DAMPMAX XSLP_DAMPMIN XSLP_DAMPSHRINK XSLP_DAMPSTART XSLP_DCLIMIT XSLP_DEFAULTIV XSLP_DEFAULTSTEPBOUND XSLP_DELAYUPDATEROWS XSLP_DELTA_A XSLP_DELTA_R XSLP_DELTA_X XSLP_DELTA_Z XSLP_DELTACOST XSLP_DELTACOSTFACTOR XSLP_DELTAFORMAT XSLP_DELTAMAXCOST XSLP_DELTAOFFSET XSLP_DELTAZLIMIT XSLP_DERIVATIVES XSLP_DJTOL XSLP_ECFCHECK XSLP_ECFTOL_A XSLP_ECFTOL_R XSLP_EQTOL_A XSLP_EQTOL_R XSLP_ERRORCOST XSLP_ERRORCOSTFACTOR XSLP_ERRORMAXCOST XSLP_ERROROFFSET XSLP_ERRORTOL_A XSLP_ERRORTOL_P XSLP_ESCALATION XSLP_ETOL_A XSLP_ETOL_R XSLP_EVALUATE XSLP_EVTOL_A XSLP_EVTOL_R XSLP_EXCELVISIBLE XSLP_EXPAND XSLP_EXTRACVS XSLP_EXTRAUFS XSLP_EXTRAXVITEMS XSLP_EXTRAXVS XSLP_FUNCEVAL XSLP_GRANULARITY XSLP_INFEASLIMIT XSLP_INFINITY XSLP_ITERLIMIT XSLP_ITOL_A XSLP_ITOL_R XSLP_IVNAME XSLP_LOG XSLP_MAXTIME XSLP_MAXWEIGHT XSLP_MEM_CALCSTACK XSLP_MEM_COEF XSLP_MEM_COL XSLP_MEM_CVAR XSLP_MEM_DERIVATIVES XSLP_MEM_EXCELDOUBLE XSLP_MEM_FORMULA XSLP_MEM_FORMULAHASH XSLP_MEM_FORMULAVALUE XSLP_MEM_ITERLOG XSLP_MEM_RETURNARRAY XSLP_MEM_ROW XSLP_MEM_STACK XSLP_MEM_STRING XSLP_MEM_TOL XSLP_MEM_UF XSLP_MEM_VALSTACK XSLP_MEM_VAR XSLP_MEM_XF XSLP_MEM_XFNAMES XSLP_MEM_XFVALUE XSLP_MEM_XROW XSLP_MEM_XV XSLP_MEM_XVITEM XSLP_MEMORYFACTOR XSLP_MINUSDELTAFORMAT XSLP_MINUSERRORFORMAT XSLP_MINWEIGHT XSLP_MIPALGORITHM XSLP_MIPCUTOFF_A XSLP_MIPCUTOFF_R XSLP_MIPCUTOFFCOUNT XSLP_MIPCUTOFFLIMIT XSLP_MIPDEFAULTALGORITHM XSLP_MIPFIXSTEPBOUNDS XSLP_MIPITERLIMIT XSLP_MIPLOG XSLP_MIPOCOUNT XSLP_MIPOTOL_A XSLP_MIPOTOL_R XSLP_MIPRELAXSTEPBOUNDS XSLP_MTOL_A XSLP_MTOL_R XSLP_MVTOL XSLP_OBJSENSE XSLP_OBJTOPENALTYCOST XSLP_OCOUNT XSLP_OTOL_A XSLP_OTOL_R XSLP_PENALTYCOLFORMAT XSLP_PENALTYROWFORMAT XSLP_PLUSDELTAFORMAT XSLP_PLUSERRORFORMAT XSLP_PRESOLVE XSLP_PRESOLVEPASSLIMIT XSLP_PRESOLVEZERO XSLP_SAMECOUNT XSLP_SAMEDAMP XSLP_SBLOROWFORMAT XSLP_SBNAME XSLP_SBROWOFFSET XSLP_SBSTART XSLP_SBUPROWFORMAT XSLP_SCALE XSLP_SCALECOUNT XSLP_SHRINK XSLP_SLPLOG XSLP_STOL_A XSLP_STOL_R XSLP_STOPOUTOFRANGE XSLP_TIMEPRINT XSLP_TOLNAME XSLP_UNFINISHEDLIMIT XSLP_UPDATEFORMAT XSLP_UPDATEOFFSET XSLP_VALIDATIONTOL_A XSLP_VALIDATIONTOL_R XSLP_VCOUNT XSLP_VLIMIT XSLP_VTOL_A XSLP_VTOL_R XSLP_WCOUNT XSLP_WTOL_A XSLP_WTOL_R XSLP_XCOUNT XSLP_XLIMIT XSLP_XTOL_A XSLP_XTOL_R XSLP_ZERO Double control parameters
Integer control parameters
Memory control parameters
Memory control parameters are integer controls which can be used to define a minimum number of items for which space should be provided. For example, to allow space for at least 5000 coefficients, set XSLP_MEM_COEF to 5000.
Normally, Xpress-SLP will expand the memory required for items as the number grows. However, this process can be inefficient in the use of available memory and can, in any case, take time. If the system runs out of memory, then an error message will be produced and normally a list of current memory requirements will be printed. Alternatively, the library function XSLPuprintmemory can be used to print the memory currently in use. The following is an example of the information produced:
Arrays and dimensions: Array Item Used Max Allocated Memory Size Items Items Memory Control MemList 28 103 129 4K String 1 206891 219888 215K XSLP_MEM_STRING Xv 16 1282 2000 32K XSLP_MEM_XV Xvitem 48 1382 1600 75K XSLP_MEM_XVITEM UserFunc 80 2 1000 79K XSLP_MEM_UF IntlFunc 80 45 48 4K Vars 136 1685 2000 266K XSLP_MEM_VAR Coef 40 4631 4633 181K XSLP_MEM_COEF Formula 48 1415 2000 94K XSLP_MEM_FORMULA ToknStak 16 10830 13107 205K XSLP_MEM_STACK Cols 48 8163 8192 384K XSLP_MEM_COL Rows 40 4596 5120 200K XSLP_MEM_ROW Xrows 48 1607 2000 94K XSLP_MEM_XROW FormValu 16 3182 3184 50K XSLP_MEM_FORMULAVALUE XPRSrow 4 12883 13155 52K XPRScol 4 12883 13155 52K XPRScoef 8 12883 13155 103K XPRSetyp 1 12883 13155 13K CalcStak 24 1 1000 24K XSLP_MEM_CALCSTACK XPRSrhrw 4 1492 1494 6K XPRSrhel 8 1492 1494 12KUsed Items is the number of items actually in use; Max Items is the number currently allocated, which is reflected in the Allocated Memory figure. Where there is an option to change the size of the allocation, the name of the memory control parameter is given. So, for example, to set the initial size of the Xrows array to 1650, use the following:
XSLPsetintcontrol(Prob, XSLP_MEM_XROW, 1650);This will have two effects: the array will be allocated from the start with 1650 items, so there will be no need to expand the array as items are loaded or created; the array will be large enough to hold the items required but will have less unused space, so there will be more memory available for other arrays if necessary.
The following is a list of the memory control parameters that can be set with an indication of the type of array for which they are used. The current value can be retrieved using XSLPgetintcontrol, or the full set can be listed using XSLPuprintmemory.
String control parameters
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