across
(To be removed) Establish relationship between component variables and nodes
across will be removed in a future release. Use
            equations instead. For more information, see Define Relationship Between Component Variables and Nodes.
Syntax
across( variable1, node1.variableA, node2.variableB
)
Description
across( variable1, node1.variableA, node2.variableB
) establishes the following relationship between the three arguments:
                variable1 is assigned the value (node1.variableA –
                node2.variableB). All arguments are variables. The first one is not
            associated with a node. The second and third must be associated with a node.
The following rules apply:
- All arguments must have consistent units. 
- The second and third arguments do not need to be associated with the same domain. For example, one may be associated with a one-phase electrical domain, and the other with a 3-phase electrical. 
- Either the second or the third argument may be replaced with - []to indicate the reference node.
Examples
If a component declaration section contains two electrical nodes, p
            and n, and a variable v = { 0, 'V' }; specifying
            voltage, you can establish the following relationship in the setup section:
across( v, p.v, n.v );
This defines voltage v as an Across variable from node
                p to node n.