SimEvents vs Step

SimEvents is desktop software for modeling message-based communication and other event-driven processes. It uses a discrete-event simulation engine and component library, and can combine event-based models with Simulink time-based models for large hybrid systems. Blocks represent entity creation and destruction, queues, service times, routing, attributes, and event responses. Resource Pool, Resource Acquirer, and Resource Releaser blocks model resource allocation, while repeated simulations can support optimization. Analysis includes latency, throughput, packet loss, queue lengths, delays, and average service times. Users can simulate and debug models, inspect queue contents, visualize entity activity, and build custom visualization tools. Output statistics aggregate measures, and Sequence Viewer displays messages, events, and entities. MATLAB Discrete Event System and Discrete Event Chart blocks allow custom behavior. Listed applications include communication networks, software and hardware architectures, forecasting, capacity planning, and supply chain management. SimEvents requires MATLAB and Simulink, runs on Windows, Mac, and Linux, and has a 30-day trial with paid licensing.

Step is a free Linux desktop application for exploring physical systems through interactive simulations. Users can change body and force properties while a simulation runs. Supported models include two-dimensional classical mechanics, molecular dynamics, sound waves, and deformable bodies, with particles, damped springs, gravitational and Coulomb forces, rigid bodies, and collision handling. Step calculates unit conversions, expressions, error propagation, and solver error estimates. Explicit and implicit solvers reach 8th order, with optional adaptive timesteps; most require GSL. Graph, meter, and tracer tools visualize results, while a controller changes properties using keyboard shortcuts. Tutorials, example experiments, object information, and an integrated Wikipedia browser provide learning material. More examples can be downloaded through KNewStuff. Expression calculations such as unit conversion require libqalculate. Step is GPL-2.0+ software, and its StepCore library can be used separately. The listed release is Step 26.08.2, released 2026-10-08.