1. A method for calculating a function value of a data-based function model in a control unit which has an arithmetic unit and a separate model calculation unit, wherein the data-based function model has multiple partial models, comprising: providing input data to the model calculation unit; transmitting a calculation address, which indicates an address of first configuration data in a memory unit, to a direct memory access (DMA) unit; retrieving the first configuration data, which contain parameters and node data for calculating a first partial model, from the memory unit, and transmitting the first configuration data to the model calculation unit; ascertaining a first partial function value of the first partial model based on the input data; storing the first partial function value in the model calculation unit; and repeating the following steps until a predefined stop condition is satisfied: retrieving additional configuration data, which contain parameters and node data for calculating an additional partial model, from the memory unit, and transmitting the relevant additional configuration data to the model calculation unit; ascertaining an additional partial function value of the additional partial model based on the input data; and adding the additional partial function value to the value stored in the model calculation unit.