Stateflow User's Guide

Defining Function Data

Before you can finish a function, you need to define all or some of its data. Use the following steps to defined data for a Stateflow function:

1. Specify the data properties (data type, initial value, and so on) for the function arguments and return value.
• Change data properties directly in the Contents pane of the Model Explorer by clicking values in the displayed columns for a data row.
• Change data properties in the Data dialog for a data.

• If you right-click a data row in the Model Explorer and select Properties from the resulting pop-up menu, its Data dialog appears. See Setting Data Properties in the Data Dialog for information on setting data properties.

1. The following restrictions apply to setting properties for the arguments and return value of a function:
   • Each argument and the return value can be a scalar or matrix of values.
   • A function can have only one return.
   • Arguments cannot have initial values.

2. Create any additional data items that the function might need to process its programming when it is called.

1. A function can access its own data or data belonging to parent states or the chart. The items that you create for the function itself can have any of the following scopes:
   • Local

   • A local data item persists from invocation to invocation. For example, if the item is equal to 1 when the function returns from one invocation, the item will equal 1 the next time the function is invoked.

   • Temporary

   • Stateflow creates and initializes a copy of a temporary item for each invocation of the function.

   • Constant

   • Constant data retains its initial value through all invocations of the function.

• All data items (other than arguments and return values) parented by a function can be initialized from the workspace. However, only local items can be saved to the workspace.

It is not necessary to assign local data to an embedded MATLAB function. You can declare local data in an embedded MATLAB function simply by using it. In this case, Stateflow uses first use assignments to determine the type, size, and value of the local data. See Declaring Variables Implicitly in Simulink documentation for specific rules in declaring local data in Embedded MATLAB functions.

Programming Functions

Calling Functions in Stateflow

© 1994-2005 The MathWorks, Inc.