Path: utzoo!attcan!uunet!bu.edu!snorkelwacker!apple!das
From: das@Apple.COM (David Shayer)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Why can't the Mac add?
Message-ID: <45108@apple.Apple.COM>
Date: 25 Sep 90 02:00:53 GMT
References: <45060@apple.Apple.COM> <20360@dime.cs.umass.edu>
Organization: Apple Computer Inc., Cupertino, CA
Lines: 20

Let's try this one more time, then I promise to go away and stop
bothering all you nice people.  

I know what happens when you convert 0.2 to binary.  I know literally
how precision is lost in the base conversion.  I know what a mantissa and
an exponent are.  That's not my question.

I know that the sample program I posted is bad programming style,
but it illustrates the question well. So stop flaming me about it.
(I don't usually write code like that, I promise.)

huh-HUM (throat clearing noises.)
The calculator DA can do this math correctly.  If you add 0.2 fifty
times, you get 10.0.  Exactly.  Not 9.999999 or 10.0000001.  I tried
changing my float variable to an extended, as someone suggested.  No dice.
Does the calculator DA have its own special math package?  (If so, the
dCad calculator does too.)  No one seems to think SANE has calls which
take care of this.  So why does it work in the calculator?

David