more sun and vax diffs

[Doug Gwyn <gwyn>]

"Log10 of zero IS infinity."

That is a good example of the problem with trying to support arithmetic
on non-numbers.  The quoted statement is incorrect in any case, since
10 ^ infinity is definitely not zero.  I would also object to the more
correct statement "Log10 of zero is minus infinity", if infinity is
being treated on an equal basis with real numbers.  Correct treatment
of infinite and infinitesimal quantities is the province of the field
of "nonstandard analysis", and these simplistic approaches will just
get na"ive users into trouble.

Let me ask another one:  What is the square root of -1?  Anyone who
says "i" or "-i" is wrong; the square root is a double-valued function
and must be treated VERY carefully or bogus answers will be obtained.
This is explained in any good complex analysis course.