Claims directed to methods of simulation, design or modelling typically comprise features which fall under the category of mathematical methods or of methods for performing mental acts. Hence, the claimed subject-matter as a whole may fall under the exclusions from patentability mentioned under Art. 52(2)(a)Art. 52(2)(c) and Art. 52(3) (see G‑II, 3.3 and 3.5.1).

The methods considered in this section, however, are at least partially computer-implemented so that the claimed subject-matter as a whole is not excluded from patentability. When determining which features contribute to the technical character of the invention, the same principles as outlined in G‑II, 3.3 apply.

The computer-implemented simulation of the behaviour of an adequately defined class of technical items, or specific technical processes, under technically relevant conditions qualifies as a technical purpose (T 1227/05). Examples are the numerical simulation of the performance of an electronic circuit subject to 1/f noise or of a specific industrial chemical process.

Such computer-implemented simulation methods cannot be denied a technical effect merely on the ground that they precede actual production and/or do not comprise a step of manufacturing the physical end product.

In contrast, the simulation of non-technical processes, such as a marketing campaign, an administrative scheme for transportation of goods or determining a schedule for agents in a call centre, does not represent a technical purpose. In addition, a generic limitation, such as "simulation of a technical system", does not define a relevant technical purpose.

In the context of computer-aided design of a specific technical object (product, system or process), the determination of a technical parameter which is intrinsically linked to the functioning of the technical object, where the determination is based on technical considerations, is a technical purpose (T 471/05, T 625/11).

For example, in a computer-implemented method of designing an optical system, the use of a particular formula for determining technical parameters, such as refractive indices and magnification factors, for given input conditions so as to obtain optimal optical performance makes a technical contribution. As another example, determining by iterative computer simulations the maximum value that an operating parameter of a nuclear reactor may take without risking rupture of a sleeve due to stress makes a technical contribution.

In contrast, where the computer-aided determination of the technical parameters depends on decisions to be taken by a human user and the technical considerations for taking such decisions are not specified in the claim, a technical effect of improved design cannot be acknowledged since such an effect would not be causally linked to the claim features (T 835/10).

If a computer-implemented method results merely in an abstract model of a product, system or process, e.g. a set of equations, this per se is not considered to be a technical effect, even if the modelled product, system or process is technical (T 49/99, T 42/09). For example, a logical data model for a family of product configurations has no inherent technical character, and a method merely specifying how to proceed to arrive at such a logical data model would not make a technical contribution beyond its computer-implementation. Likewise, a method merely specifying how to describe a multi-processor system in a graphical modelling environment does not make a technical contribution beyond its computer-implementation. Reference is made to G‑II, 3.6.2 related to information modelling as an intellectual activity.