Version 5.5 (R2007b) Simulink® Fixed Point™ Software Release Notes

Version 5.5 (R2007b) Simulink^® Fixed Point™ Software

This table summarizes what's new in Version 5.5 (R2007b):

New features and changes introduced in this version are

• New Signal Logging Options in the Fixed-Point Tool

• Add, Subtract, and Sum Blocks Use an Accumulator Data Type

• Cast Operations with Net Bias Use an Intermediate Data Type

• Non-Matrix-Wise Parameter Scaling Modes Removed

New Signal Logging Options in the Fixed-Point Tool

In this release, the Fixed-Point Tool includes new options that provide batch control of signal logging for models and subsystems. These options allow you to enable or disable logging for multiple signals simultaneously, based on the location of signals in a model hierarchy and whether the signals have names. For more information, see the documentation for the fxptdlg function in the Simulink^® Reference.

Add, Subtract, and Sum Blocks Use an Accumulator Data Type

In previous releases, the Add, Subtract, and Sum blocks used a user-specified output data type to perform all operations. This behavior might have caused precision loss and saturation during intermediate operations, producing unexpected results. In this release, these blocks use an ideal accumulator data type when performing intermediate operations. Consequently, the Add, Subtract, and Sum blocks now produce more precise results, and the Real-Time Workshop^® product generates less saturation code for them.

Cast Operations with Net Bias Use an Intermediate Data Type

Data type conversions with net bias involve an intermediate addition operation. In previous releases, blocks that perform such casts used the output data type's container to compute the addition operation. This behavior might have caused extra saturation, producing unexpected results. In this release, data type conversions can use an ideal data type when performing all intermediate operations. By reducing or eliminating intermediate saturations, cast operations now produce more accurate results, and the Real-Time Workshop product generates more efficient code for them.

Non-Matrix-Wise Parameter Scaling Modes Removed

In previous releases, the Gain and Weighted Moving Average blocks contained a parameter named Parameter scaling mode whose options included the following scaling modes:

• Best Precision: Element-wise

• Best Precision: Row-wise

• Best Precision: Column-wise

• Best Precision: Matrix-wise

In this release, only the Best Precision: Matrix-wise setting is available, and it is now simply named Best precision. On the Parameter Attributes pane of the Gain or Weighted Moving Average block parameter dialog box, use the Data Type Assistant to specify Best precision for the Scaling control.

Compatibility Considerations

Pre-R2007b models that contain Gain or Weighted Moving Average blocks whose Parameter scaling mode option specifies a non-matrix-wise setting will be updated automatically when loaded in R2007b. That is, the Simulink^® software will change non-matrix-wise settings to Best precision, which now represents matrix-wise-best-precision scaling. Consequently, affected blocks might generate results that differ from those obtained in previous releases.

Version 5.6 (R2008a) Simulink® Fixed Point™ Software

Version 5.4.1 (R2007a+) Simulink® Fixed Point™ Software