Re: mistake in manpage for expr

[Paul Eggert]

"Vajzovic, Tom" <address@hidden> writes:

> Of course, five minus seven is negative two, but the _difference_
> between five and seven is positive two, since differences are always
> positive.

Your usage disagrees with the traditional terminology.  For example,
<http://en.wikipedia.org/wiki/Arithmetic> says "if the minuend is
smaller than the subtrahend, the difference will be negative".

Also see page 105 of:

H. D. Huskey, Technical Developments: Characteristics of the Institute
for Numerical Analysis Computer, Mathematical Tables and Other Aids to
Computation, Vol. 4, No. 30. (Apr., 1950), pp. 103-108.
<http://links.jstor.org/sici?sici=0891-6837%28195004%294%3A30%3C103%3ATDCOTI%3E2.0.CO%3B2-E>

This shows that the idea that differences can be negative goes quite a
way back in computing.