We give an alternative and unified derivation of the general framework developed
in the last few years for analyzing nonstationary time series. A different approach
for handling the resulting variational problem numerically is introduced. We further
expand the framework by employing adaptive finite element algorithms and ideas
from information theory to solve the problem of finding the most adequate model
based on a maximum-entropy ansatz, thereby reducing the number of underlying
probabilistic assumptions. In addition, we formulate and prove the result establishing
the link between the optimal parametrizations of the direct and the inverse problems
and compare the introduced algorithm to standard approaches like Gaussian mixture
models, hidden Markov models, artificial neural networks and local kernel methods.
Furthermore, based on the introduced general framework, we show how to create new
data analysis methods for specific practical applications. We demonstrate the application
of the framework to data samples from toy models as well as to real-world problems
such as biomolecular dynamics, DNA sequence analysis and financial applications.
Keywords
nonstationary time series analysis, nonstationary data
analysis, clustering, finite element method