Rational Arithmetic For Mini-Computers

Unknown author (1977-09)

This report describes research done at the Artificial Intelligence Laboratory of the Massachusetts Institute of Technology. Support for the laboratory's artificial intelligence research is provided in part by the Advanced Research Projects Agency of the Department of Defense under Office of Naval Research contract N00014-75-A-0643.

Working Paper

A representation for numbers using two computer words is discussed, where the value represented is the ratio of the corresponding integers. This allows for better dynamic range and relative accuracy than single-precision fixed point, yet is less costly than floating point arithmetic. The scheme is easy to implement and particularly well suited for mini-computer applications that call for a great deal of numerical computation. The techniques described have been used to implement a mathematical function subroutine package for a mini-computer as well as a number of applications programs in the machine vision and machine manipulation area.