Chapter  2 introduced algorithm design, with an emphasis on the systematic development of case-by-case distinctions that need to be taken into account when solving a given problem. For the description of an algorithm, this examination yielded two basic elements for the ordering of instructions:
  • The sequence, or simple sequential execution of instructions

  • The case-by-case distinction (frequently called a branching), or the execution of instructions dependent upon the validity of a condition

The algorithm used to solve a quadratic equation (see Sect.  2.3) made extensive use of both elements.


  1. Wirth, N.: Program development by step-by-step refinement. Commun. ACM 14(4), 221–227 (1971) CrossRefMATHGoogle Scholar

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© Springer Fachmedien Wiesbaden 2015

Authors and Affiliations

  • Johannes Brauer
    • 1
  1. 1.NORDAKADEMIE, Hochschule der WirtschaftElmshornGermany

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