In this chapter, I present a specific view of signal processing. I provide the basic definitions regarding what - according to our view - signal processing should be seen as, and I elucidate in this perspective the meaning of a selection of relevant algorithms and approaches.

We ask whether empirical finance market data (Financial Stress Index, swap and equity, emerging and developed, corporate and government, short and long maturity), with their recently observed alternations between calm periods and financial turmoil, could be described by a low-dimensional...