Hi all,

I just stumbled upon this paper by William Kahan, a Professor at Berkeley that is well known for his work on the first Intel math co-processor, and the development of IEE 754 (plus a lot of other stuff). I took a course with him at Berkeley, and the man is brilliant. So brilliant that is is very hard to follow him, as a student, if you are not so sharp. I'm not, and I just squeeked by and missed a great deal of what he tried to teach. I did gain a good appreciation of the complexity of floating point arithmetic, however. Here is the paper as a PDF:

http://www.cs.berkeley.edu/%7ewkahan/MgtkMath.pdf

There's a lot of other good stuff on his web page at:

http://www.cs.berkeley.edu/%7ewkahan/

THe paper is entitled "Marketing versus Mathematics". In particular, take a look at the section on Quattro Pro on Page 13, for a nice discussion of binary arithmetic displayed as decimal, which is an often brought up subject in the Python newsgroups. He discusses how you'd really have to display more than the 15 digits that Quattro displayed, to avoid confusion.

""" But no such cure can be liberated from little annoyances: 0.8 entered would display as 0.80000000000000004 to 17 sig. dec.; """ At the Python prompt:

0.8

0.80000000000000004

More evidence that the current Python way is "best", if confusing to newbies. This would be another good paper to point people towards that ask about floating point on the newsgroups.

-Chris