The researcher's activity involves a quick examination of a mathematical method in order to treat a complex system. The chapters of this book, by way of presentation, ensure easy access to mathematical techniques without the need for an inherent passage and the range of axiomatic proofs of certain theorems or relations, which is not often useful, given that they have was once demonstrated by a particular author in the history of mathematics. In fact, this is often a stereotype of most math books that become unattractive, dull when axiomatic takes precedence over concrete applications.