The NETFLOW Procedure

Macro Variable _ORNETFL

The NETFLOW procedure creates and initializes a SAS macro variable called _ORNETFL. After exiting the procedure, you can use %put &_ORNETFL; to view details about the optimization.

When the network simplex method is used, the value of _ORNETFL consists of the following parts:

ERROR_STATUS, indicating the existence or absence of any errors
OPT_STATUS, the stage of the optimization, or what solution has been found

Ideally, at the end of a PROC NETFLOW run in which the network simplex method is used, _ORNETFL has the following value:

   ERROR_STATUS=OK OPT_STATUS=OPTIMAL OBJECTIVE=x
   SOLUTION=OPTIMAL

At the end of a PROC NETFLOW run in which the interior point algorithm is used, _ORNETFL should have the following value:

   ERROR_STATUS=OK SOLUTION=OPTIMAL OBJECTIVE=x
   ITERATIONS=x ITERATING_TIME=x SOLUTION_TIME=x

Nontrailing blank characters that are unnecessary are removed. If the preprocessor detects that a problem with a network component is infeasible, and you specify that the interior point algorithm should be used, _ORNETFL has the following value:

  ERROR_STATUS=OK SOLUTION=INFEASIBLE
  ITERATIONS=0 ITERATING_TIME=0 SOLUTION_TIME=0

The same value is assigned to the _ORNETFL macro variable if the preprocessor detects that an LP problem is infeasible.

Table 6.6 lists alternate values for the _ORNETFL value parts.

Table 6.6: PROC NETFLOW _ORNETFL Macro Values

Keyword	Value	Meaning
ERROR_STATUS	OK	No errors
	MEMORY	Memory request failed
	IO	Input/output error
	DATA	Error in the data
	BUG	Error with PROC NETFLOW
	SEMANTIC	Semantic error
	SYNTAX	Syntax error
	UNKNOWN	Unknown error
OPT_STATUS	START	No optimization has been done
	STAGE_1	Performing stage 1 optimization
	UNCON_OPT	Reached unconstrained optimum, but there are side constraints
	STAGE_2	Performing stage 2 optimization
	OPTIMAL	Reached the optimum
OBJECTIVE	objective	Total cost or profit
MINFLOW	minflow	If MAXFLOW and MAXIMIZE are specified at the same time
MAXFLOW	maxflow	If MAXFLOW is specified
SHORTEST_PATH	shortpath	If SHORTPATH is specified
LONGEST_PATH	longpath	If SHORTPATH and MAXIMIZE are specified at the same time
SOLUTION	NONOPTIMAL	More optimization is required
	STAGE_2_REQUIRED	Reached unconstrained optimum, stage 2 optimization is required
	OPTIMAL	Have determined the optimum
	INFEASIBLE	Infeasible; no solution exists
	UNRESOLVED_OPTIMALITY_OR_FEASIBILITY	The optimization process stops before optimality or infeasibility can be proven.
	MAXITERB_OPTION_STOPPED_OPTIMIZATION	The interior point algorithm stops after performing maximal number of iterations specified by the MAXITERB= option