Hi Dave, Thanks, more insights!
I was only concerned that there was some correction in one of the messages. And since there was only 3 minutes between them, i didn't know which might be the corrected one. They showed up here out of order. I responded to the one with the later timestamp.
No, mia culpa.
Just post one of them. Otherwise, things can get very confusing.
Done.
Actually, it's 64 bits. 32 bit fp wouldn't get you anywhere near 18 digits.
Darn, of course, you're right! Senior moment for me!
Since the inputs to that function are ints, then the output will be IEEE floats. that also means that the == comparisons in the crosspoint() function are precise.
THAT is a very valuable insight Dave, thanks!
Actually, the base change is already happening. Using Decimal would probably reduce the number of base changes. And if you create the numbers as Decimal objects, then they'll propagate through the crosspoint() function correctly. However, even though the decimal module supports log and sqrt, I don't know how to do trig with it.
Well, as trig is *core essential* to polyhedra maths, I *have* to use *lots* of it!
Incidentally, I didn't suggest the fractions module, since you're presumably going to be doing trig on the results, so I don't see the benefit.
Yes. Core maths is +,-,*,/,sin,cos,tan (and their inverses), sqrt, ^2,^3, (ie, exponentials), etc off hand.
BTW, I misspoke earlier. The module name is decimal. The class name within that module is Decimal.
A minor thing to me, a non programmer, but I do understand that being very precise is very important to programmers, so thank you! John. _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
