mpc is a complex floating-point library with exact rounding.
It is based on the mpfr floating-point library (www.mpfr.org),
which is itself based on the GNU MP library (www.swox.se/gmp/).

A complex number is represented in cartesian coordinates by its real
and imaginary parts, as described in:

  Vladik Kreinovich and Juergen Wolff von Gudenberg,
  "An optimality criterion for arithmetic of complex sets",
  Geombinatorics, 2000, Vol. 10, No. 1, pp. 31-37.
  http://www.cs.utep.edu/vladik/longvita.html#JournalCS