The simulation environment Diana (Dynamic simulation and numerical analysis tool) is suitable for the numerical analysis of problems in chemical engineering and systems biology. The key aspects are object-oriented models, a numerical kernel, and the use of the scripting language Python as a powerful command line interface. Models are created with the modelling tool ProMoT and are implemented in C++, but can be manipulated interactively as a simple Python instance. Diana contains different implementations of numerical methods well suited for chemical process engineering and systems biology. Within numerical methods it is possible to use sparse matrix implementations of basic algorithms such as linear algebra routines. Different nonlinear algebraic and differential-algebraic solvers are implemented, based on existing third party open-source code and can be applied depending on the special properties of the model. The simulation environment also allows the use of continuation methods for steady states and singular points of the dynamical model.