APG Composer combines a 3-voice FM synthesizer with an implementation of the Logique Analogique sequencer, which triggers notes when a weighted sum of different signals exceeds a threshold. APG Composer was created from a Simulink* model without writing app-specific code, using the Audio Plugin Generator source code.
Compared to the iPad version of APG Composer, the user interface for the iPhone app has been simplified by controlling several parameters using just one knob. The underlying sound synthesis algorithm however remains the same.
*Simulink is a registered trademark by The Mathworks, Inc.