The Neural Net Fitting app leads you through solving a data-fitting problem using a two-layer feed-forward network. It helps you select data, divide it into training, validation, and testing sets, define the network architecture, and train the network. You can select your own data from the MATLAB^® workspace or use one of the example datasets. After training the network, evaluate its performance using mean squared error and regression analysis. Further analyze the results using visualization tools such as a regression fit or histogram of the errors. You can then evaluate the performance of the network on a test set. If you are not satisfied with the results, you can retrain the network with modified settings or on a larger data set.