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Re: [Mingw-users] msvcrt printf bug




On 05-Feb-17 04:29, KHMan wrote:
> On 2/5/2017 10:29 AM, Emanuel Falkenauer wrote:
>> Hi KHMan,
>>
>> [...]
>>> The phrasing in Rick Regan's articles may mislead some folks.
>> I can't help to interpret your "folks" as derogatory and patronizing,
>> but anyway...
> Keith Marshall was way more blunt, nobody complained, not even a peep.

There is a difference: Keith was indeed pretty "blunt" in judging 
certain assertions (mine, among others) to be "total and utter nonsense" 
(or something in that vein)... but that was his perfect right: he argued 
about an ARGUMENT (which he thought to be stu.... , huh, incorrect!), 
NOT about WHO presented it - he never called the other side "folks".

> I carefully write a diplomatic sentence about an issue we disagree
> about, you jump all over me.

I'm just trying to explain to you that the objective here is to come to 
some conclusions we could all agree on - NOT to arrive to EXclusions 
just because someone is supposedly "folks". Please, refrain from using 
that word: it's really demeaning - which (I hope!) is not what you want.

> Just who is always channeling all the "derogatory and patronizing"
> vibe anyway?

I applauded you several times when I found your arguments valid, and I 
presented counter-ARGUMENTS when I found it was not the case - isn't 
that what a normal DEBATE is all about?. But I never called you "folks" 
or, indeed, pretended that you had "still much to learn" (as you told 
Alexandru the other day) - it's just a question of respect for your 
opponent.

>
>>> [...]
>>>
>>> Articles by R Regan, B Dawson, etc. discusses where are some exact
>>> tick marks on a line of all floating point values. These tick
>>> marks are the exact values of the binary formats of floating point
>>> floats and doubles. This concept is only useful if your value is
>>> precisely on a tick mark -- an artificial condition that can only
>>> be meaningfully enforced in mathematical studies like what they
>>> are doing.
>> Well, if BY DEFINITION their "tick marks" are exactly where a binary
>> float can EVER fall, how would you construct "your value" that is NOT
>> "precisely on a tick mark"? Unless they made a mathematical mistake (I
>> admit I didn't read the detail of their papers to spot one), your
>> objection has simply no sense whatsoever.
> A value can be somewhere on the line (say I want to store 0.1),
> its closest IEEE binary representation is a tick mark. That tick
> mark is not exactly 0.1, but very close. It's approximate. Then I
> calculate A*A. I get something very close to 0.01. When rounded
> appropriately, I might get 0.01. It's approximate.

Sure... but who EVER argued otherwise?? Nobody - certainly not me, anyway!

As K. Frank eloquently (and superbly, I'd say) explained, you are 
conflating two issues that have NOTHING in common, i.e.
  - (1) what the result SHOULD be if floats were real reals of infinite 
precision (though they are NOT), and
  - (2) what the result ACTUALLY IS - and how it should ideally be 
PRINTED/represented in decimal.
Alexandru, myself and (it appears) at least a few others, would like to 
have a decimal print that could (at least) reliably distinguish between 
ANY two binary floats, and represent two identical binary floats THE 
SAME way (that's the (2) above), even though we ALL KNOW that each of 
the binary floats is the result of an "approximate" computation(s) 
(that's the (1) above).

> Well, I read postings by Keith, Earnie, Eli, Peter, Mitch, etc. --
> I think this one side is all on the same page on floating-point.
>
> I really don't know how else we can explain things to the other side.

Pretty simple: stop conflating completely UNrelated issues.  ;-) Float 
computations are fundamentally IMprecise (we all KNOW that!), but their 
(imprecise) value, whatever it is, should be PRINTED as PRECISELY as 
possible.

Best,

Emanuel

>
>> Lo and behold: contrary to popular belief of some "folks", not all
>> mathematicians are loonies who have no idea how real world (e.g.
>> computers) work.  ;-)
>>
>> Best,
>>
>> Emanuel
>>
>> [...]


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