=== Online Introductions ===
[http://www.maths.manchester.ac.uk/~higham/narep/narep416.pdf Interval analysis in MATLAB] Note: The INTLAB toolbox for Matlab is not entirely compatible with this interval package for GNU Octave.
For example, INTLAB additionally supports intervals in mid-rad form with complex values, INTLAB has no representation of an empty interval and INTLAB provides some features that this interval package is missing. However, basic operations can be compared and should be compatible for common intervals.
=== Moore's fundamental theroem of interval arithmetic ===