TIB: Re: TI-86 math error?

To: <ti-basic@lists.ticalc.org>
Subject: TIB: Re: TI-86 math error?
From: "Zachary Lute" <draco@netnitco.net>
Date: Mon, 5 Oct 1998 17:10:16 -0500
Delivered-To: ti-basic-outgoing@towerguard.unix.edu.sollentuna.se
Reply-To: ti-basic@lists.ticalc.org



>I found a bug in a program I made.  It turns out that it is not my fault
>but somthing the ti-86 does. Why does this give me the wrong answer?
>The TI-86 gives 2*10^-9 or 2E-9.  The answer should be .002.  I get the
>right answer if I type 6E-6/3E-3.  Which is useless since I need to be
>using a variable for my program.


I would call this a bug in the TI-86.  As near as I can tell, it has to do
with the way the calculator chooses to store information, which I am not an
expert on.  I had a lot of trouble with this when doing complex equations
involving imaginary numbers, hence needing the calculator.  If you do a
simple equation such as 5+2-->x, the calculator stores the answer of the
equation (7) to the variable.  Hence x-7=0.  I can't explain it, but if you
do something like 2(5^(1/2)) --> x  (Sorry about the fractional exponent,
couldn't figure out a radical symbol) It does not store the answer
(4.472135955).  I don't know exactly what it does, but x-4.472135955 does
NOT equal 0 as it should, but rather equals -4E-13.  Just to be sure, I
manually subtracted 4.4.. - 4.4... and got 0.  I don't know how it works,
but I thought I'd put in my experience.