MaraDNS is a security-aware DNS implementation. It can be configured as an authoritative DNS server or as a "recursive" DNS cache. Versions up to 1.0.xx have been released to the public domain. Versions after 1.1.00 are copyrighted but are distributed with a liberal licence (a simplified BSD licence without the advertising clause.)
... the quadratic equation
<math>ax^2+bx+c=0</math>
in terms of the coefficients a, b and c, which are assumed to be real (but see below for generalizations) ...