Re: Fuzzy Logic Operating Systems

Feb 13, 2006 3 Replies
S

In comp.os.linux.misc Jean-David Beyer wrote: :> : Let me remark that the the things I _insist_ upon in a piece of computer : hardware or operating system is predictability, repeatability, and : deterministic behavior. If I do the same thing (e.g., run a program with the



So you don't use any programs on binary computers that do floating point math? If so, ever heard of round-off error or wonder why



5/5 is not necessarily equal to 2-1?

Don't foget, ALL binary computers work in finite precision, so insist away!



Stan


Stan Bischof ("stan" at the below domain) www.worldbadminton.com
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You are missing the point. What you get when doing floating point arithmetic on any given machine, with a given compilation system _is_ deterministically defined. So if floating point 5 divided by floating point 5 does not give exactly floating point zero (although in every case I know of, it does), and floating point 2 minus floating point 1 does not give exactly floating point

1 (and it does in every case I know of), the floating point difference between the ratio and the difference, above, is _always the same_ or the machine is broken.

You do not get it.

.~. Jean-David Beyer Registered Linux User 85642. /V\ PGP-Key: 9A2FC99A Registered Machine 241939. /( )\ Shrewsbury, New Jersey http://counter.li.org ^^-^^ 18:20:00 up 24 days, 9:48, 4 users, load average: 4.15, 4.16, 4.16
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S

In comp.os.linux.misc Jean-David Beyer wrote: :> :> Don't foget, ALL binary computers work in finite precision, so insist :> away! :> : You do not get it.

Sure- if you use exactly the same software running on exactly the same hardware starting from exactly the same initial conditions, and with all exactly the same inputs, in a deterministic system you end up in exactly the same ending point.

However, that would apply to all binary computers running any OS/software, barring true random events like alpha-particle induced flipped bits and the like, no?

can you name ANY OS/software that isn't determinitstic given this restrictivce definition?

I was pointing out that if you are a little less restrictive then you end up with all sorts of affects - like FP bit errors- that creep in and appear to lend a randomness.

regards

Stan

Stan Bischof ("stan" at the below domain) www.worldbadminton.com
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Jean-David> You are missing the point. What you get when doing Jean-David> floating point arithmetic on any given machine, with a Jean-David> given compilation system _is_ deterministically Jean-David> defined. So if floating point 5 divided by floating Jean-David> point 5 does not give exactly floating point zero Jean-David> (although in every case I know of, it does),=20

In very case I know of, it doesn't. 5/5 !=3D 0 That's simple arithmetic that one learns in primary school.

Jean-David> and floating point 2 minus floating point 1 does not Jean-David> give exactly floating point 1 (and it does in every Jean-David> case I know of), the floating point difference between Jean-David> the ratio and the difference, above, is _always the Jean-David> same_ or the machine is broken.

--=20 Lee Sau Dan =A7=F5=A6u=B4=B0 ~= {@nJX6X~}

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