Re: Infinite precision floating-point
- From: André Thieme <address.good.until.2005.jul.05@xxxxxxxxxxx>
- Date: Fri, 27 May 2005 02:54:24 +0200
josephoswaldgg@xxxxxxxxxxx schrieb:
André Thieme wrote:
As I said, there is (at least in my belief) no analog world. "Analog" is something we invented to describe "something that gets very small or exact". We will find things whose first 20 decimal places are exactly the ones of an irrational number. We would need better measuring methods to see that it is *not* an irrational number. Anyway, it doesn't matter because for any irrational number you tell me, there is a rational number with which we can represent in our real world this irrational one.
You have never seen Pi, i.e. circles.
This is a meaningless statement. Have you ever "seen" a rational number? A negative number? Have you ever "seen" a cons cell? (to bring things back into comp.lang.lisp territory). Have you ever "seen" an algorithm?
We can "see" *material things* (when the lights are on) but also *depictions* of immaterial ones. Some things cannot be seen directly, but can be thought about (and rigourously calculated with) nonetheless.
The world might be digital, but we can still do calculus, so apparently we can make an analog world even if one isn't provided for our convenience. Giving up calculus because it isn't "real" is almost the opposite of what should be done: better to give up reality, instead. :-)
If you need a good irrational number, start up Maxima and use %e or %pi.
Oohoo! Stop! I don't want to get rid of calculus! It is fine that we have it. Although everything in our practical world can (and gets) be done with rational numbers it is nice to have calculus. Having irrational numbers makes things much easier, in calculus. I have no problem with mathematical constructs that only exist in math and have nothing to do with our real world. Just doing it for doing the science can be stimulating for several people.
And my "you have never seen Pi" was meant in a practicle way. While coming back to the mathematical view we can represent Pi. Anyway, even when talking in the mathematical world there are irrational numbers that we can't represent (concretely). We can only say "let x be an irrational number". This then stands for any irrational number, but unlike Pi or e we can't express them with an algorithm, as this algorithm would have to be as long as the row of decimal places - but in that fact the best algorithm would be just enumbering all digits of the number.
André -- .
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