1. An explanation of the "atom floating point" bug,
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At 01:58 PM 03/20/2000 +1200, you wrote:
<SNIP!>
>
>...you failed to answer my
>question again. jiri
Last night Lewis posted some code which I modified to narrow down his problem.
My code looked something like the snippet below:
atom b
integer a
b=att - floor (att)
b=b*10
a=floor(b)
? att
? b
? a
If att=4.1 then b=att-floor(att) should be equal to .1 and b*10 should be equal
to 1
but a is returned as 0 rather than as 1.
Irv (after massaging my code) showed that att is actually
att=4.09999999999999964473
and
b=0.99999999999999644729
which explains why a=0 because floor rounds down to the next lower integer.
So what I **think** Irv was trying to point out was an atom is really
**approximation** of a float and **NOT** actually accurate as a c float of the
same value.
If you add .00001 to any atom you will better approximate the value of the
original floating point number.
Hope that is a little clearer explanation
Joel H. Crook
Manager, Information Services
Certified Novell Administrator
Microsoft Certified Professional, OS Specialist
Kellogg & Andelson Accountancy Corp.
14724 Ventura Blvd. 2nd Floor
Sherman Oaks, CA 91403
(818) 971-5100
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<html><div>At 01:58 PM 03/20/2000 +1200, you wrote:</div>
<div><SNIP!></div>
<div>></div>
<div>>...you failed to answer my</div>
<div>>question again. jiri</div>
<br>
<div>Last night Lewis posted some code which I modified to narrow down
his problem. My code looked something like the snippet
below:</div>
<br>
<div>atom b </div>
<div>integer a </div>
<div>b=att - floor (att) </div>
<div>b=b*10 </div>
<div>a=floor(b) </div>
<div>? att </div>
<div>? b </div>
<div>? a </div>
<br>
<div>If att=4.1 then b=att-floor(att) should be equal to .1 and b*10
should be equal to 1</div>
<div>but a is returned as 0 rather than as 1.</div>
<br>
<div> Irv (after massaging my code) showed that att is
actually</div>
<div>att=4.09999999999999964473</div>
<br>
<div>and</div>
<br>
<div>b=0.99999999999999644729</div>
<br>
<div>which explains why a=0 because floor rounds down to the next lower
integer.</div>
<br>
<div>So what I **think** Irv was trying to point out was an atom is
really **approximation** of a float and **NOT** actually accurate
as a c float of the same value.</div>
<br>
<div> If you add .00001 to any atom you will better approximate the
value of the original floating point number.</div>
<br>
<div>Hope that is a little clearer explanation</div>
<br>
<br>
Joel H. Crook<br>
<br>
Manager, Information Services<br>
<font size=1>Certified Novell Administrator<br>
Microsoft Certified Professional, OS Specialist<br>
<br>
</font><b>Kellogg & Andelson Accountancy Corp.<br>
</b><font size=1>14724 Ventura Blvd. 2nd Floor<br>
Sherman Oaks, CA 91403<br>
(818) 971-5100<br>
</font></html>
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