Architecting and designing > Structured analysis and design > Modeling with decomposition diagrams > Generating automatic decomposition diagrams
  
Generating automatic decomposition diagrams
You can run a command to automatically generate a decomposition diagram with symbols representing the functions of an encyclopedia, or any portion of the encyclopedia you choose. The operation also automatically generates symbols representing all the symbols and definitions from any chosen diagram, or the hierarchy within any diagram.
There is no practical limit to the number of levels or symbols that can be represented. It is possible, however, for the symbols to stretch beyond the limits of the available pages on the diagram. If that occurs, click Tools > Session Options; then modify the setting in MaxDrawArea in the SA.INI editor to increase the diagram size to the maximum limit.
1 Click Draw > Decomposition, and then select one of these commands:
Functional Decomposition
A functional decomposition diagram represents the functions in the chosen diagram and any related child diagrams. The functional decomposition diagram is generated from the functions in a diagram that you select.
Diagram Hierarchy
A diagram hierarchy diagram represents all symbols on all diagrams descending from the original diagram that you select. The diagram hierarchy diagram is generated from the functions in a selected diagram. The diagram type and symbol type are displayed on the symbols as a graphic comment.
Diagram Explosion
A diagram explosion diagram represents a single diagram, and includes all the symbols and all their definitions and subordinate definitions.
The Select for Automatic Decomposition dialog box opens. This is the version of the dialog box for diagram explosion diagrams.
This graphic is described in the surrounding text.
2 In the Name box, type a diagram name or partial name.
3 In the Type list, select the diagram type from which the decomposition is generated.
You can leave the type at [all data flow diagram types] for functional decomposition, [all diagram types] for other auto-decomposition types, or select a specific diagram type, such as DFD Yourdon/DeMarco.
4 Click Search.
A list of diagrams appears.
5 Select a diagram.
You can click the file folders to expand the names of symbols, some of which might also have closed file folders pictured next to them, which indicates that more levels are available.
Functional Decomposition diagrams depict processes, so only process symbols or the equivalent are available for selection. The selected process forms the top of the decomposition. Only one process can be selected at a time.
For diagram hierarchy or diagram explosion diagrams, only one diagram can be selected at a time.
Note If you select a large, complex diagram as the source, a diagram might be generated that is bigger than the number of available pages: for example, if you generate a diagram explosion diagram from a complex source and include all symbols, such as rectangular and line, and all subordinate definitions. However, you can increase the default diagram draw area as described above.
6 For diagram hierarchy diagrams, select the line symbols and rectangular symbols that you want to include.
For diagram explosion diagrams, select the line symbols and subordinate definitions that you want to include.
Subordinate definitions include data elements that define data structures, for example.
7 To generate the diagram, click Build.
See also
Modeling with decomposition diagrams