Neutrices and External Numbers : A Flexible Number System

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Author(s): Bruno Dinis, Imme van den Berg

Neutrices and External Numbers: A Flexible Number System introduces a new model of orders of magnitude and of error analysis, with particular emphasis on behaviour under algebraic operations. The model is formulated in terms of scalar neutrices and external numbers, in the form of an extension of the nonstandard set of real numbers. Many illustrative examples are given. The book starts with detailed presentation of the algebraic structure of external numbers, then deals with the generalized Dedekind completeness property, applications in analysis, domains of validity of approximations of solutions of differential equations, particularly singular perturbations. Finally, it describes the family of algebraic laws characterizing the practice of calculations with external numbers.


  • Presents scalar neutrices and external numbers, a mathematical model of order of magnitude within the real number system.
  • Outlines complete algebraic rules for the neutrices and external numbers
  • Conducts operational analysis of convergence and integration of functions known up to orders of magnitude
  • Formalises a calculus of error propagation, covariant with algebraic operations
  • Presents mathematical models of phenomena incorporating their necessary imprecisions, in particular related to the Sorites paradox



The book Neutrices and External numbers: A Flexible Number System by Bruno Dinis and Imme van den Berg provides a remarkable presentation of the system of external numbers. It is a rigorous and convenient mathematical theory that provides a strong foundation for a complete doctrine of orders of magnitude — the art of neglecting—so present in the scientific approach. This subject is exposed in a pedagogical and comprehensive way by multiplying the points of view and the applications.

—Retired Professor Guy Wallet, La Rochelle University, France

[. . .] The latest addition to the outstanding CRC Press 'Monographs and Research Notes In Mathematics' series, Neutrices and External Numbers: A Flexible Number System by Bruno Dinis and Imme van den Berg (who is an Associated Professor in Mathematics at the University of Evora, Portugal and whose main area of interest lies in non-standard analysis) is enhanced for academia with an informative five page Foreword, as well as the inclusion of a twelve page Bibliography and a four page Index -- making is a significant and unreservedly recommended addition to professional, college, and university library Advanced Mathematics collections and supplemental curriculum lists. It should be noted for students, academia, and non-specialist readers with an interest in the subject that "Neutrices and External Numbers" is also available in a digital book format

Midwest Book Review

EAN: 9781000005387