RE: Really strange problem, for very bright people

I understand that clearly, but what I'm failing to understand is how the
following occurs...

1.035 * 4.32765 * 1.673

gives different answers to

1.673 * 1.035 * 4.32765 and 4.32765 * 1.673 * 1.035

They are the same numbers, just in a different sequence....

(Please note, these are not the numbers in my original equation, I've just
written some very simplified numbers to illustrate the problem)

The only thing I can think of, is that the order of the calculation, and
therefore the order of precision loss, has a different outcome on the final
answer....

Very strange...

Anyway, thanks for all the help...


-----Original Message-----
From: jimdelilah [mailto:[email protected]]
Sent: 08 August 2003 17:24
To: [email protected]
Subject: Re: [Delphi] Really strange problem, for very bright people


This may or may not help you understand.

Try this and see what value is in vCalc_e2 when the code executes.

var vCalc_e2 : Extended;
begin
   vCalc_e2 := 239.752763879;   // line 1
   if (vCalc_e2 = 0) Then       // line 2
      ShowMessage(' equals 0 ');
end


you will see (at line 2)that vCalc_e2 will be 239.75276388.

vCalc_e2 := 239.752763879;   // line 1
vCalc_e2  = 239.75276388;

This is because there is a *huge* set of numbers that cannot be
represented in 8 or 10 bytes of data.   It is kinda like trying to
draw a rainbow with a box of 10 crayons.  Sure you can get someting
close, but under close exanimation you will see that the resolution
is poor.


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