28. The computer-readable storage medium of claim 21 , wherein step b) comprises: training a first machine learning system using a set of training input data and a set of training output data, wherein each of the training input data is a profile model having a set of profile parameters with the same profile parameters as the initial profile model, and wherein each of the training output data is a diffraction signal.
28. The computer-readable storage medium of claim 21 , wherein step b) comprises: training a first machine learning system using a set of training input data and a set of training output data, wherein each of the training input data is a profile model having a set of profile parameters with the same profile parameters as the initial profile model, and wherein each of the training output data is a diffraction signal. 29. The computer-readable storage medium of claim 28 , wherein the set of training output data is generated based on the set of training input data using a modeling technique prior to training the machine learning system.