On the geometry of the smallest circle enclosing a finite set of points

Lance D. Drager, Jeffrey M. Lee, Clyde F. Martin

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


A number of numerical codes have been written for the problem of finding the circle of smallest radius in the Euclidean plane that encloses a finite set P of points, but these do not give much insight into the geometry of this circle. We investigate geometric properties of the minimal circle that may be useful in the theoretical analysis of applications. We show that a circle C enclosing P is minimal if and only if it is rigid in the sense that it cannot be translated while still enclosing P. We show that the center of the minimal circle is in the convex hull of P. We use this rigidity result and an analysis of the case of three points to find sharp estimates on the diameter of the minimal circle in terms of the diameter of P.

Original languageEnglish
Pages (from-to)929-940
Number of pages12
JournalJournal of the Franklin Institute
Issue number7
StatePublished - Oct 2007


  • Smallest enclosing circle


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