The Matrix Editor is a tool for handling graphs by representing them as matrices, containing two axes and related cells. Figure 4–28 shows a Matrix Editor window.

The Matrix Editor follows the same rules as other MetaEdit+ tools. Each element, whether it is on an axis or in a cell, has dialog(s) for adding, viewing and editing further information about the element. Modifications made to an element via the Matrix Editor are stored to the repository and reflected in other tools.

The Matrix Editor is capable of representing and editing any graph of any type, even if the graph was originally created with a Diagram or Table Editor. Thus the Matrix Editor can be used both to view graphs first made as graphical diagrams, like Data Flow Diagrams, and to work with specifically matrix-based languages (like Business Systems Planning, which is almost totally matrix based).

The Matrix Editor offers the special functions needed for working with matrix based graphs. Some examples of these are diagonalization, subsystem decomposition, and viewing.

The Matrix Editor window (as shown in Figure 4–28) consists of three parts: menu bar, toolbar area and the matrix itself.

The toolbar area can show up to three toolbars: action tools, object types and relationship types (Figure 4–29). The object and relationship toolbars change according to the current language to show the available object and relationship types in that language. The commands on the action toolbar are fixed, and are (from left to right):

Depending on the modeling language in use, quick-access buttons for various generators may appear next to Delete button.

The visibility of the toolbars in each Matrix Editor window can be set from the View | Toolbar menu. Default visibility and layout of toolbars can be set in the Options Tool (see Section 3.1.3).

The matrix area consists of a horizontal axis, a vertical axis, and a matrix of cells between them. The axes contain representations of objects, and each cell shows the binary relationships or roles between the corresponding objects on the horizontal and vertical axes. Note that because a matrix only has two axes, it can only show relationships with two roles, i.e. binary relationships. N-ary relationships and their roles are not visible in a matrix.