The industrial tool Matlab/Simulink is widely used in the design of embedded systems. The main feature of this tool is its ability to model in a common formalism the software and its physical environment. This makes it very useful for validating the design of embedded software using numerical simulation. However, the formal verification of such models is still problematic as Simulink is a programming language for which no formal semantics exists. In this article, we present an operational semantics of a representative subset of Simulink which includes both continuous-time and discrete-time blocks. We believe that this work gives a better understanding of Simulink and it defines the foundations of a general framework to apply formal methods on Simulink's high level descriptions of embedded systems.

Hybrid systems are a widely used model to represent and reason about control-command systems. In an industrial context, these are often implemented in Simulink and their validity is checked by performing many numerical simulations in order to test their behavior with various possible inputs. In this article, we present a tool named HySon which performs set-based simulation of hybrid systems with uncertain parameters, expressed in Simulink. Our tool handles advanced features such as non-linear operations, zero-crossing events or discrete sampling. It is based on well-known efficient numerical algorithms that were adapted to handle set-based domains. We demonstrate the performance of our method on various examples.