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GAMS — The Solver Manuals - Available Software

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444 OSL<br />

sets the amount of memory used to 10 MB. Mymodel is the name of the model as specified by the model<br />

statement. In order to be effective, the assignment of the model suffix should be made between the model and<br />

solve statements.<br />

Option<br />

workspace<br />

optfile<br />

cheat<br />

cutoff<br />

prioropt<br />

Description<br />

Gives OSL x MB of workspace. Overrides the memory estimation.<br />

Instructs OSL to read the option file osl.opt.<br />

Cheat value: each new integer solution must be at least x better than the previous one.<br />

Can speed up the search, but you may miss the optimal solution. <strong>The</strong> cheat parameter is<br />

specified in absolute terms (like the OPTCA option). <strong>The</strong> OSL option improve overrides<br />

the <strong>GAMS</strong> cheat parameter.<br />

Cutoff value. When the Branch and Bound search starts, the parts of the tree with an<br />

objective worse than x are deleted. Can speed up the initial phase in the Branch and<br />

Bound.<br />

Instructs OSL to use priority branching information passed by <strong>GAMS</strong> through the<br />

variable.prior parameters.<br />

5 Summary of OSL Options<br />

All these options should be entered in the option file osl.opt after setting the mymodel.optfile parameter to 1.<br />

<strong>The</strong> option file is not case sensitive and the keywords must be given in full. Examples for using the option file<br />

can be found at the end of this section.<br />

5.1 LP Algorithmic Options<br />

Option<br />

crash<br />

iterlim<br />

method<br />

pdgaptol<br />

presolve<br />

reslim<br />

simopt<br />

scale<br />

toldinf<br />

tolpinf<br />

workspace<br />

Description<br />

crash an initial basis<br />

iteration limit<br />

solution method<br />

barrier method primal-dual gap tolerance<br />

perform presolve. Reduce size of model.<br />

resource limit<br />

simplex option<br />

perform scaling<br />

dual feasibility tolerance<br />

primal feasibility tolerance<br />

memory allocation<br />

5.2 MIP Algorithmic Options<br />

Option<br />

bbpreproc<br />

cutoff<br />

cuts<br />

degscale<br />

improve<br />

incore<br />

iweight<br />

maxnodes<br />

maxsols<br />

optca<br />

optcr<br />

Description<br />

branch and bound preprocessing<br />

cutoff or incumbent value<br />

allocate space for extra cuts<br />

scale factor for degradation<br />

required level of improvement over current best integer solution<br />

keep tree in core<br />

weight for each integer infeasibility<br />

maximum number of nodes allowed<br />

maximum number of integer solutions allowed<br />

absolute optimality criterion<br />

relative optimality criterion

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