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In page Mathematical model:

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Any model which is not pure white-box contains some parameters that can be used to fit the model to the system it is intended to describe. If the modeling is done by an artificial neural network or other machine learning, the optimization of parameters is called training, while the optimization of model hyperparameters is called tuning and often uses cross-validation.[1] In more conventional modeling through explicitly given mathematical functions, parameters are often determined by curve fitting.[citation needed]