Simulink® Fixed Point™

Working With the Fixed-Point Advisor

Introduction to the Fixed-Point Advisor

The Fixed-Point Advisor provides a set of tasks to facilitate converting a floating-point model or subsystem to an equivalent fixed-point representation. You can use the Fixed-Point Advisor to prepare a model for conversion and obtain an initial scaling to use as the starting point for refinement and exploration inside the Fixed-Point Tool.

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Running the Fixed-Point Advisor

1. Open a model.

2. Start the Fixed-Point Advisor by

   • Typing fpcadvisor('model_name/subsystem_name') at the MATLAB^® command line.

   • Selecting a subsystem and then selecting Fixed-Point > Fixed-Point Advisor from the Tools menu.

   • Right-clicking a subsystem block and then selecting Fixed-Point > Fixed-Point Advisor from the subsystem context menu.

   The Fixed-Point Advisor dialog opens.

3. Select the Fixed-Point Advisor folder in the Task Hierarchy pane.

4. Run the advisor by

   • Selecting Run to Failure from the Run menu.

   • Right-clicking the Fixed-Point Advisor folder and selecting Run to Failure from the folder context menu.

   The Fixed-Point Advisor runs the tasks in order until a task fails. A waitbar is displayed while each task runs.

5. Review the results. If a task fails because input parameters are not specified, select an Input Parameter. Then continue running to failure by right-clicking the task and selecting Continue from the context menu. If the task fails for a different reason, fix the task as described in Fixing a Task Failure.

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Fixing a Task Failure

Tasks fail when there is a step for you to take to convert your model from floating-point to fixed-point. For more information on why a specific task fails, see the Fixed-Point Advisor Reference.

You can fix a failure using three different methods:

• Fix the failure by following the instructions in the Analysis Result box. Use this method to fix failures individually.

• Fix the failure using the Action box. Use this method to automatically fix all failures. See Automatically Fixing Failures.

• Fix the failure using the Model Advisor Results Explorer. Use this method to batch fix failures. See Batch Fixing Failures

Note   A warning result is meant for your information. You can choose to fix the reported issue, or to move on to the next task.

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Automatically Fixing Failures

You can automatically fix failures using the Action box. The action box applies all of the recommended actions listed in the Analysis Result box.

Caution   You should review the Analysis Result box prior to automatically fixing failures to ensure that you want to apply all of the recommended actions.

Automatically fix all failures within a task using the following steps:

1. In the Action box, click Modify All.

   The Action Result box displays the a table of changes.

2. To verify that the task now passes, in the Analysis box, click Run This Task.

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Batch Fixing Failures

If a task fails and you want to explore the results and make batch changes, use the following steps.

1. In the Analysis box, click Explore Result.

   The Model Advisor Result Explorer dialog box opens.

2. Use the Model Advisor Result Explorer to modify block parameters.

3. When you have finished making changes, in the Fixed-Point Advisor dialog box, click Run This Task to see if the changes you made results in the task passing. Continue fixing failures and rerunning the task until the task passes.

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Fixed-Point Advisor

Tutorial: Converting a Model from Floating- to Fixed-Point