Figure 4.60: The Barrier Tab in XPRESS Options Dialog Box
You can change the barrier file options for XPRESS by choosing XPRESS parameters from the Options menu and then pressing the Barrier tab. This will display the barrier options for XPRESS in the dialog box as shown below:
Figure 4.60: The Barrier Tab in XPRESS Options Dialog Box
| Option Name | MPL Name | Solver Param | ParamNr | Type | Default | Min | Max |
|---|---|---|---|---|---|---|---|
| Barrier Algorithm | list | ||||||
| Cross-Over Control | DoCrossover | Crossover | 8044 | list | -1 | -1 | 1 |
| Dense Column Removal | DENSECOL | DenseColLimit | 8086 | int | 0 | 0 | MAXINT |
| Ordering Algorithm | CholeskyFact | BarOrder | 8080 | list | 0 | 0 | 3 |
| Cholesky Factorization | PushCholesky | CholeskyAlg | 8046 | list | 1 | 0 | 1 |
Selects whether the algorithm solves the primal or dual problem. The Barrier Algorithm option has the following possible selections:
| Automatic selection (0) | |
| Primal problem. (1) | |
| Dual problem. (2) |
The Cross-Over Control option has the following possible selections:
| No cross-over (0) | (only available if presolve is Off). |
| Cross-over to a basic solution (1) |
Columns with more elements than this value are considered to be dense, and a special procedure is used to handle them in the Cholesky factorization
Specifies the Ordering Algorithm for the Cholesky factorization. The Ordering Algorithm option has the following possible selections:
| Automatic selection (0) | |
| Minimum degree. (1) | |
| Minimum local fill. (2) | |
| Nested dissection. (3) |
Specifies the type of Cholesky factorization used. The available options are:
| Pull Cholesky (0) | |
| Push Cholesky. (1) |