@techreport{and-sto-98-circtr,
  author = {{Marcus Vin{\'\i}cius} A. Andrade and Jorge Stolfi},
  title = {Exact Algorithms for Circles on the Sphere},
  institution = {Institute of Computing, Univ. of Campinas},
  number = {IC-98-08},
  pages = {16},
  year = 1998,
  month = apr,
  comment = {Superseded by~\cite{and-sto-98-circ}.},
  abstract = {We develop exact algorithms for geometric operations on general circles and circular arcs on the sphere, using integer homogeneous coordinates. The algorithms include testing a point against a circle, computing the intersection of two circles, and ordering three arcs out of the same point. These operations allow robust manipulation of maps on the sphere, providing a reliable framework for GIS, robotics, and other geometric applications.}
}