Chapter 17
Rate of Change in a Process
By interrogating a set variable, ASPL sources the variable: if any change in the data is detected, then the variable is archived and reassigned with the sourced data. Therefore, ASPL set variables can be viewed as differential variables, and you can use the command playsim to play the similarity on such a set variable. The command causes an iteration aggregating the similarity between the historical archived data over time, and since ASPL variables maintain the time of their creation, then the command aggregates and calculates the Rate of Change in Dissimilarity of the Process represented by the set variable.Furthermore, you can use the command playchanges to display the rate of change in the elements of a process represented by a set variable and its archive. While one can play different set operations on differential variables, but the fundamental operator is gD,`ks~ which is read as "the labinated pure symmetric difference on the group such that the element attributes differ"; and this is the default operator implied in playchanges.
Finally, you can play a set operator on intermittent data by using the command playop. This command can simply display the set operation on the variable and its archive instance, or intermittently between two instances (marking the change in state), or continuously as data is aggregated over time.
