Input data
At the moment ‘time-series data links’, ‘subscripting data links’ as well as combinations of these links are supported. A data link is a link of a Vensim model element to a database table column.
A subscripting data link (SDL) is used to link a Vensim constant to a database table column and run one independent simulation for every row value in this column. Multiple SDLs may be defined to link more than one constant to every independent simulation run (Fig. 1; A).
Fig. 1. A) Database table with two subscripting data links (SDL); B) Database table with two time series links (TSL)
A time-series data link (TSL) is used to assign database table columns as time series to Vensim variables (Fig. 1; B). Multiple TSLs of a single or of multiple database tables may be assigned to a single VENSIM model.
As an additional functionality, SDLs may optionally be equipped with a simulation timestamp (see also section 6). For instance, a first SDL may be assigned to the initial simulation time 0 of a VENSIM variable element and a second SDL may be assigned to a final time step 100 of the same VENSIM variable. SimSyn linearly interpolates between the first and the second SDL values in the course of its integration.
In some instances combinations of SDL and TSL are required. In cases where SDLs and TSLs are assigned to a VENSM model, the time series are duplicated and assigned to every single run of the SDL. SDLs and TSLs may refer to the same or different database tables. For this type of data-linked simulation, larger computational overhead is to be expected (see also section 10).