The Network Solver (Experimental)

General Options

You can specify the following general options, which have the same meaning for multiple algorithms.

GRAPH_DIRECTION=DIRECTED | UNDIRECTED DIRECTION=DIRECTED | UNDIRECTED

specifies directed or undirected graphs.

Table 8.5: Values for the GRAPH_DIRECTION= Option

Option Value	Description
DIRECTED	Requests a directed graph. In a directed graph, each link $(i,j)$ has a direction that defines how something (for example, information) might flow over that link. In link $(i,j)$ , information flows from node $i$ to node $j$ ( $i \rightarrow j$ ). The node $i$ is called the source (tail) node, and $j$ is called the sink (head) node.
UNDIRECTED	Requests an undirected graph. In an undirected graph, each link $\{ i,j\}$ has no direction and information can flow in either direction. That is, $\{ i,j\} = \{ j,i\}$ .

By default, GRAPH_DIRECTION=UNDIRECTED.

INCLUDE_SELFLINK

includes self links in the graph definition—for example, $(i,i)$ —when an input graph is read. By default, when the network solver reads the LINKS= data, it removes all self links.

LOGFREQ=number

controls the frequency with which an algorithm reports progress from its underlying solver. This setting is recognized by the traveling salesman problem and minimum-cost flow algorithms. You can set number to 0 to turn off log updates from underlying algorithms.

LOGLEVEL=number | string

controls the amount of information that is displayed in the SAS log. This setting sets the log level for all algorithms. Table 8.6 describes the valid values for this option.

Table 8.6: Values for LOGLEVEL= Option

number	string	Description
0	NONE	Turns off all procedure-related messages in the SAS log
1	BASIC	Displays a basic summary of the input, output, and algorithmic processing
2	MODERATE	Displays a summary of the input, output, and algorithmic processing
3	AGGRESSIVE	Displays a detailed summary of the input, output, and algorithmic processing

By default, LOGLEVEL=BASIC.

MAXTIME=number

specifies the maximum time spent calculating results. The type of time (either CPU time or real time) is determined by the value of the TIMETYPE= option. The value of number can be any positive number; the default value is the positive number that has the largest absolute value that can be represented in your operating environment. The clique, cycle, minimum-cost network flow, and traveling salesman problem algorithms recognize the MAXTIME= option.

TIMETYPE=number | string

specifies whether CPU time or real time is used for the MAXTIME= option for each applicable algorithm. Table 8.7 describes the valid values of the TIMETYPE= option.

Table 8.7: Values for TIMETYPE= Option

number	string	Description
0	CPU	Specifies units of CPU time
1	REAL	Specifies units of real time