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| The OPTLP Procedure |
| ODS Tables |
PROC OPTLP creates two ODS (Output Delivery System) tables by default unless you specify a value other than 1 for the PRINTLEVEL= option. One table is a summary of the input LP problem. The other is a brief summary of the solution status. PROC OPTLP assigns a name to each table it creates. You can use these names to reference the table when using the ODS to select tables and create output data sets. For more information about ODS, see SAS Output Delivery System: Procedures Guide.
If you specify a value of 2 for the PRINTLEVEL= option, then a third table, "ProblemStatistics," is produced. This table contains information about the problem data. For more information, see the section Problem Statistics.
ODS Table Name |
Description |
PRINTLEVEL= |
|---|---|---|
ProblemSummary |
Summary of the input LP problem |
1 (default) |
SolutionSummary |
Summary of the solution status |
1 (default) |
ProblemStatistics |
Description of input problem data |
2 |
A typical output of PROC OPTLP is shown in Figure 17.2.
| Problem Summary | |
|---|---|
| Problem Name | ADLITTLE |
| Objective Sense | Minimization |
| Objective Function | .Z.... |
| RHS | ZZZZ0001 |
| Number of Variables | 97 |
| Bounded Above | 0 |
| Bounded Below | 97 |
| Bounded Above and Below | 0 |
| Free | 0 |
| Fixed | 0 |
| Number of Constraints | 56 |
| LE (<=) | 40 |
| EQ (=) | 15 |
| GE (>=) | 1 |
| Range | 0 |
| Constraint Coefficients | 383 |
You can create output data sets from these tables by using the ODS OUTPUT statement. This can be useful, for example, when you want to create a report to summarize multiple PROC OPTLP runs. The output data sets corresponding to the preceding output are shown in Figure 17.3, where you can also find (at the row following the heading of each data set in display) the variable names that are used in the table definition (template) of each table.
| Problem Summary |
| Obs | Label1 | cValue1 | nValue1 |
|---|---|---|---|
| 1 | Problem Name | ADLITTLE | . |
| 2 | Objective Sense | Minimization | . |
| 3 | Objective Function | .Z.... | . |
| 4 | RHS | ZZZZ0001 | . |
| 5 | . | ||
| 6 | Number of Variables | 97 | 97.000000 |
| 7 | Bounded Above | 0 | 0 |
| 8 | Bounded Below | 97 | 97.000000 |
| 9 | Bounded Above and Below | 0 | 0 |
| 10 | Free | 0 | 0 |
| 11 | Fixed | 0 | 0 |
| 12 | . | ||
| 13 | Number of Constraints | 56 | 56.000000 |
| 14 | LE (<=) | 40 | 40.000000 |
| 15 | EQ (=) | 15 | 15.000000 |
| 16 | GE (>=) | 1 | 1.000000 |
| 17 | Range | 0 | 0 |
| 18 | . | ||
| 19 | Constraint Coefficients | 383 | 383.000000 |
| Solution Summary |
| Obs | Label1 | cValue1 | nValue1 |
|---|---|---|---|
| 1 | Solver | Dual simplex | . |
| 2 | Objective Function | .Z.... | . |
| 3 | Solution Status | Optimal | . |
| 4 | Objective Value | 225494.96316 | 225495 |
| 5 | . | ||
| 6 | Primal Infeasibility | 2.273737E-13 | 2.273737E-13 |
| 7 | Dual Infeasibility | 1.909584E-13 | 1.909584E-13 |
| 8 | Bound Infeasibility | 0 | 0 |
| 9 | . | ||
| 10 | Iterations | 95 | 95.000000 |
| 11 | Presolve Time | 0.00 | 0 |
| 12 | Solution Time | 0.00 | 0 |
Problem Statistics
Optimizers can encounter difficulty when solving poorly formulated models. Information about data magnitude provides a simple gauge to determine how well a model is formulated. For example, a model whose constraint matrix contains one very large entry (on the order of 
) can cause difficulty when the remaining entries are single-digit numbers. The PRINTLEVEL=2 option in the OPTLP procedure causes the ODS table "ProblemStatistics" to be generated. This table provides basic data magnitude information that enables you to improve the formulation of your models.
The example output in Figure 17.4 demonstrates the contents of the ODS table "ProblemStatistics."
| Problem Statistics | |
|---|---|
| Number of Constraint Matrix Nonzeros | 8 |
| Maximum Constraint Matrix Coefficient | 3 |
| Minimum Constraint Matrix Coefficient | 1 |
| Average Constraint Matrix Coefficient | 1.875 |
| Number of Objective Nonzeros | 3 |
| Maximum Objective Coefficient | 4 |
| Minimum Objective Coefficient | 2 |
| Average Objective Coefficient | 3 |
| Number of RHS Nonzeros | 3 |
| Maximum RHS | 7 |
| Minimum RHS | 4 |
| Average RHS | 5.3333333333 |
| Maximum Number of Nonzeros per Column | 3 |
| Minimum Number of Nonzeros per Column | 2 |
| Average Number of Nonzeros per Column | 2 |
| Maximum Number of Nonzeros per Row | 3 |
| Minimum Number of Nonzeros per Row | 2 |
| Average Number of Nonzeros per Row | 2 |
The variable names in the ODS table "ProblemStatistics" are Label
, cValue, and nValue.
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