Dear all,
this is my first mail to this mailing list, I'm not sure this is the
correct one to post this topic.
I noticed a strange behavior of the format function. I'm not sure it can
be considered as a bug.
If I use
format('%.3f', [-0.0001])
the resulting string is
-0.000
and not
0.000
Why?
On Thursday 12 October 2006 12:16, Andrea Mauri wrote:
Dear all,
this is my first mail to this mailing list, I'm not sure this is the
correct one to post this topic.
I noticed a strange behavior of the format function. I'm not sure it
can be considered as a bug.
If I use
format('%.3f',
On Thu, 12 Oct 2006, Andrea Mauri wrote:
Dear all,
this is my first mail to this mailing list, I'm not sure this is the correct
one to post this topic.
I noticed a strange behavior of the format function. I'm not sure it can be
considered as a bug.
If I use
format('%.3f', [-0.0001])
the
On 12 okt 2006, at 14:22, Michael Van Canneyt wrote:
I noticed a strange behavior of the format function. I'm not sure
it can be
considered as a bug.
If I use
format('%.3f', [-0.0001])
the resulting string is
-0.000
and not
0.000
Why?
Because your number is negative... The original number
Michael Van Canneyt wrote:
Because your number is negative... The original number is taken to decide
whether it should put the - sign or not. What does delphi do ?
Michael.
___
Delphi gives 0.000 as result.
a.
Using round function I implemented the RoundTo function as in Delphi:
type
TRoundToRange = -37..37;
function RoundTo(const AValue: Double; const ADigit: TRoundToRange): Double;
var
LFactor: Double;
begin
LFactor := IntPower(10, ADigit);
Result := Round(AValue / LFactor) * LFactor;
end;
In
A week or two ago, I also found a problem with the Banker's Rounding
in Free Pascal. As far as I could see, with my tests I did, compared
to Delphi an know results with set values, there is a bug in FPC
implementation.
I might have forgotten to report it in Mantis though. I will double check.
Jonas Maebe wrote:
Not only that, but -0.000 is different from 0.000 (at least for the fpu)
Jonas
In a mathematical way of view I think that -0.000 has no meaning.
If I round something and the resulting value is zero, well zero is zero.
Not +0 or -0.
a.
Andrea Mauri wrote:
Jonas Maebe wrote:
Not only that, but -0.000 is different from 0.000 (at least for the fpu)
Jonas
In a mathematical way of view I think that -0.000 has no meaning.
Well, despite the fact that -0.000 is probably indeed wrong in this case, a
mathematical view is often
when the statement
if (-0 = 0)
is true then RoundTo schould not return an numer like -0 ?!
i think the point of view of an fpu is in the round functions not nessesary
0 is 0 and not -0
- Original Message -
From: Jonas Maebe [EMAIL PROTECTED]
To: FPC developers' list
On Thursday 12 October 2006 13:46, Micha Nelissen wrote:
Jonas Maebe wrote:
can still be one (meaning that it's a negative zero). And for some
fpu calculations this even matters.
Like ?
Divide by signed zero. That decides if the result is positive or
negative infinity. :D
Vinzent.
representable in an exact way on any IEEE standard-compliant fpu. The
Of course. But the result of format is user-oriented. User is not supposed to
know about negative zero, denormal numbers, negative infinity and the whole
IEEE 754.
If the user is supposed to understand that -0.000 means a
On 12 okt 2006, at 15:46, Micha Nelissen wrote:
Jonas Maebe wrote:
can still be one (meaning that it's a negative zero). And for some
fpu calculations this even matters.
Like ?
http://en.wikipedia.org/wiki/Negative_zero
Jonas
___
fpc-devel
On Thu, 12 Oct 2006, Jonas Maebe wrote:
On 12 okt 2006, at 15:46, Micha Nelissen wrote:
Jonas Maebe wrote:
can still be one (meaning that it's a negative zero). And for some fpu
calculations this even matters.
Like ?
http://en.wikipedia.org/wiki/Negative_zero
hehe,
Jonas
Michael Van Canneyt wrote:
Like ?
http://en.wikipedia.org/wiki/Negative_zero
Jonas being succinct as ever :)
And not answering the question ... sigh. As shown there, you never
notice the difference in result.
Micha
___
fpc-devel maillist -
Op Thu, 12 Oct 2006, schreef ???:
representable in an exact way on any IEEE standard-compliant fpu. The
Of course. But the result of format is user-oriented. User is not supposed
to know about negative zero, denormal numbers, negative infinity and the
whole IEEE 754.
http://en.wikipedia.org/wiki/Negative_zero
Jonas
Nice link: In science, #8722;0 may be used to denote a quantity which is less
than zero, but which is too small in magnitude to be rounded down to #8722;1.
Format primarily produces strings for users, not for programmers.
On 12 okt 2006, at 16:31, Micha Nelissen wrote:
Michael Van Canneyt wrote:
Like ?
http://en.wikipedia.org/wiki/Negative_zero
Jonas being succinct as ever :)
And not answering the question ... sigh. As shown there, you never
notice the difference in result.
I don't understand what you
Op Thu, 12 Oct 2006, schreef ???:
Format primarily produces strings for users, not for programmers.
Why do you think that scientific notation is used by default?
Daniël___
fpc-devel maillist - fpc-devel@lists.freepascal.org
Jonas Maebe wrote:
examples when you answered with Like?. I therefore gave a link to a
wikipedia article which shows that the sign matters e.g. when dividing
by zero (positive or negative infinity), and the article also gives some
Well I meant a real practical difference, not something at
Why do you think that scientific notation is used by default?
I personally prefer -0.000 in this case.
It's just a personal preference.
A weak argument:
If you write a program grandma should use, you can always add an extra check
if she complains (and it will be only one of the many extra
Maybe this is off topic, but some interesting information about floating
point operations could be found at
http://vod.niif.hu/index.php?lg=enmn=archiveeid=47sm=listeventsecid=85.
I recommend you to check Can we trust floating-point numbers? by Paul
Zimmermann.
ISO/IEC 10967-3 Information
Hi,
At cutils line 926, FreeMem is called for p with size strlen(p)+1. Could
it be that actually a much bigger block was allocated, and not size
strlen(p)+1 ?
Micha
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