Resolve Undecided Objective Statuses Resulting from Model Complexity

Issue

Simulink® Design Verifier™ analysis results in these undecided objective statuses due to model complexities:

  • Undecided Due to Nonlinearities — Non-linear arithmetic computations in the upstream part of the model causes imprecise calculations. After the analysis completes, the Diagnostic Viewer shows this warning:

    Simulink Design Verifier encountered nonlinear arithmetic during analysis and might not have generated test cases for some objectives.

  • Undecided Due to Stubbing — When the Simulink Design Verifier analysis encounters an unsupported block, the software stubs that block. The analysis ignores the behavior of the block, and as a result, the block output can take any value. After the analysis, the Diagnostic Viewer shows a warning similar to this one:

    Block 'ABC' is configured to operate as function exp. Analysis may be impacted due to this.

    For more information on stubbing, see Handle Model Complexities with Automatic Stubbing.

Possible Solutions

Depending upon the type of undecided objectives status, try one of these solutions.

Possible Solutions for Undecided Due to Nonlinearities Status

  • Simplify the Data Types — By default, Simulink Design Verifier interprets numerical data using the double data type which can introduce precision issues during the analysis. Simplify the data types to improve the precision of analysis representation generated from model. Specify the data types when known. For example,

    • Avoid unnecessary cast operators in data type conversions. This helps to avoid nonlinear operations during analysis​.

    • Use variables with an integer data type for timers and counters in your model.

    For more information, see Manage Model Data to Simplify the Analysis.

  • Constrain Data Type Ranges — Limiting a data type to a specific range or set of discrete values allows Simulink Design Verifier to linearize operations that would otherwise be nonlinear, making calculations easier to analyze. To constrain the data type range:

    • Add minimum and maximum values in the model inputs.

    • Use the Test Condition block or the sldv.assume function to discretize the range of inputs or intermediate signals.

    For more information, see Manage Model Data to Simplify the Analysis

  • Use Seed Test Case — Seed test cases provide inputs such that nonlinear computations are solved and the downstream logic of the model can be reached. Analyze the downstream logic that starts from the part in model involving the non-linear computations. For more information, see Add Test Cases Using Excel File.

Possible Solutions for Undecided Due to Stubbing Status

  • Follow the recommendations in the Simulink Design Verifier analysis report for the stubbed block.

  • Follow the recommendations in the message in the Diagnostic Viewer.

  • Use block replacements technique to replace the stubbed block if possible. For more information, see Perform Analysis Using Block Replacement.

See Also

Topics