Re: This calculation is just wrong / computer can't count!

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On Wed, 10 Oct 2007 11:07:43 +0100, "GT" <ContactGT_remove_@xxxxxxxxxxx> wrote:

"Joseph M. Newcomer" <newcomer@xxxxxxxxxxxx> wrote in message
news:ad7og3pku6cssog2m6r5r3hrjnh2tj4s4t@xxxxxxxxxx
You really are continuing to be terminally stupid. Why do you think that
the 7 represents
an error? It does not.

Yes is does. There is no 7 at the end of a decimal representation of 1/3. If
you include a 7 on the end and then do some subsequent calculations, you get
an invalid answer.

Tell me: did you REALLY use the Floating Point Explorer to look at this
issue? It should
be obvious to you if you did!

No I didn't and don't intend to. I fully understand where the 7 is coming
from. HOW MANY TIMES DO I HAVE TO SAY THIS, "I WANT TO KNOW HOW TO CODE SOME
MATHS THAT DOESN'T INTRODUCE THE 7".
****
And how many times do we have to explain to you that this desire cannot be realized if you
insist on using finite-precision arithmetic. It isn't going to happen. It can't happen.
It DOESN'T EVEN MAKE SENSE THAT YOU INSIST THAT IT NOT HAPPEN because to make this so you
have to introduce a very large error.
****

You really keep missing the point. You confuse precision with textual
representaiton.

NO JOE, I AM THE ONE ASKING THE QUESTION HERE - *YOU* ARE MISSING THE POINT
AND *STILL* ANSWERING SOME OTHER QUESTION.
****
You are asking a question which makes no sense, because any answer to it is wrong. See my
other post about inability to ask meaningful questions.

You say "I don't want the 7" at the same time you say "I want more accuracy". In
finite-precision IEEE-754 floating point arithmetic, these goals are incompatible. If you
want accuracy, you want the 7, if you don't want the 7, you lose accuracy. Please explain
how we can simultaneously satisfy your demands for accuracy and representation when they
are mutually incompatible? At least if you insist on using 'double' and printing out all
the digits of precision? YOUR QUESTION IS NOT BEING ANSWERED BECAUSE IT IS NOT
ANSWERABLE!!!

Since you seem to think that there is a feasible answer to an impossible question, perhaps
you should consider the nature of mathematics. Consider the Post Production problem.
Consider the Turing Machine Halting Problem. Consider the Gödel Incompleteness Theorem.
For years, mathematicians insisted that mathematics could be a closed system in which all
answers were possible. Then in the 1930s, people like Church, Turing, Gödel, and Post
came along and demonstrated that there were truly unsolvable problems in mathematics. You
have one: you want finite-precision arithmetic to work in a domain in which it cannot
work. You cannot have any floating-point unit in the history of computing give you values
that correspond to your notion of reality. It won't happen, it can't happen, and it isn't
going to happen. So we keep telling you your goal cannot be achieved, and you keep
insisting that it MUST be achieved. You are asking for something that is impossible, and
all the demanding of an answer is not going to change the fact that it is impossible to
get what you want.

We have told you that the only alternative is BIGNUM rational representations, which still
won't be right, but won't have the limitations of finite-precision floating point, and you
keep ignoring that advice. (Note that on both input and output, rational arithmetic still
fails, but it can do what you want up to certain limits)

You cannot get an answer to a question which does not have the answer you want. You once
suggested I go into politics. I think you should consider it as a career, since your
philosophy is consistent with politicians "My mind is made up, don't confuse me with
facts!" The facts are simple: your goal is impossible with double arithmetic. No amount
of demands on your part are going to change this reality to correspond to your opinion.
And nobody is going to be able to give you the answer you want because the answer you want
is inconsistent with all forms of computer reality, unless you choose an alternative
reality, and you aren't willing to accept that reality either.
joe


Joseph M. Newcomer [MVP]
email: newcomer@xxxxxxxxxxxx
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm
.

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