Rules for calculations

Desciption

Given a set of caclulation for real numbers with some special values

•  0  meaning "zero". This is a bit special value since: x / 0 is infinite. So we also need : ...
• oo meaning "infinite". This is unsigned, so it can be as well "- very much" as "+ very much"
•  ?  meaning "undetermined" is also needed for calculations like :  0 * oo

With this special values the rules below apply.

A set of calculation routines based on this special values and rules can also easily deal with overflow and underflow.
Functions calculated with such routines (like sine and log) will also give "proper" results. So tan(½ pi) will give oo.

Rules