Lennart Augustsson lenn...@augustsson.net writes:
Prelude toRational 697.04157958259998
3065621287177675 % 4398046511104
Prelude toRational 697.0415795826
3065621287177675 % 4398046511104
As you can see, both numbers are represented by the same Double.
Haskell prints a Double with the
On Aug 28, 2009, at 03:24 , Ketil Malde wrote:
What puzzled me (and the parent article indicated), was that Python
appeared to be able to work with more precision, and thus be more
numerically correct than GHC. Since it's all machine precision
floating point, this is even more strange, and I
Prelude toRational 697.04157958259998
3065621287177675 % 4398046511104
Prelude toRational 697.0415795826
3065621287177675 % 4398046511104
As you can see, both numbers are represented by the same Double.
Haskell prints a Double with the simplest number that converts back to
the same bit pattern.
On Sun, 23 Aug 2009, Lennart Augustsson wrote:
You're absolutely right. It would be easy to change logBase to have
special cases for, say, base 2 and base 10, and call the C library
functions for those. In fact, I think it's a worth while change,
since it's easy and get's better results for
I don't really care much one way or the other, but since C (math.h)
provides functions for base 2 and base 10 with some additional
accuracy, I wouldn't mind using them. For a constant base I'd expect
the extra comparison to be constant folded, so that's ok. For a
non-constant base there would be
2009/8/22 Roberto López plasterm...@hotmail.com
You get the accuracy value in Perl, but there is the same problem in
Python.
It's a bit discouraging.
You don't get an accurate answer with Perl. It just lies to you to keep you
happy in your ignorance.
$ perl -e 'printf %.22f\n,
Steve stevech1...@yahoo.com.au writes:
Also, I had a problem using floating point in Python where
round(697.04157958254996, 10)
gave
697.04157958259998
Its been fixed in the latest versions of Python:
round(697.04157958254996, 10)
697.0415795825
ghci roundN 697.04157958254996 10
2009/8/22 Roberto López plasterm...@hotmail.com:
If 4.0 / 2.0 was 1.98, it would be ok?
The real value of log10 1000 is 3 (3.0). It can be represented with accuracy
and it should be.
Well, it already can be, you just need to choose your representation properly:
logBase
On Sat, 2009-08-22 at 13:03 -0400, haskell-cafe-requ...@haskell.org
wrote:
Message: 10
Date: Sat, 22 Aug 2009 11:24:21 +0200
From: Roberto L?pez plasterm...@hotmail.com
Subject: [Haskell-cafe] Re: Is logBase right?
To: haskell-cafe@haskell.org
Message-ID: h6odg8$93...@ger.gmane.org
Content
2009/8/23 Steve stevech1...@yahoo.com.au:
On Sat, 2009-08-22 at 13:03 -0400, haskell-cafe-requ...@haskell.org
wrote:
Message: 10
Date: Sat, 22 Aug 2009 11:24:21 +0200
From: Roberto L?pez plasterm...@hotmail.com
Subject: [Haskell-cafe] Re: Is logBase right?
To: haskell-cafe@haskell.org
at 12:41 PM, Stevestevech1...@yahoo.com.au wrote:
On Sat, 2009-08-22 at 13:03 -0400, haskell-cafe-requ...@haskell.org
wrote:
Message: 10
Date: Sat, 22 Aug 2009 11:24:21 +0200
From: Roberto L?pez plasterm...@hotmail.com
Subject: [Haskell-cafe] Re: Is logBase right?
To: haskell-cafe@haskell.org
On Sun, Aug 23, 2009 at 01:25:14PM +0200, Lennart Augustsson wrote:
You're absolutely right. It would be easy to change logBase to have
special cases for, say, base 2 and base 10, and call the C library
functions for those. In fact, I think it's a worth while change,
since it's easy and
On Sun, 2009-08-23 at 15:12 +0400, Eugene Kirpichov wrote:
There is *not* the same problem in Python:
$ python
Python 2.6.2 (r262:71600, Jul 9 2009, 23:16:53)
[GCC 4.4.0 20090506 (Red Hat 4.4.0-4)] on linux2
Type help, copyright, credits or license for more information.
import math
Hello Steve,
Sunday, August 23, 2009, 5:27:48 PM, you wrote:
ghci roundN 697.04157958254996 10
697.0415795826
afair, double has 13 decimal digits precision, so your
697.04157958254996 represented by another value. you just looking for
miracles
--
Best regards,
Bulat
On Sun, 2009-08-23 at 17:36 +0400, Bulat Ziganshin wrote:
Hello Steve,
Sunday, August 23, 2009, 5:27:48 PM, you wrote:
ghci roundN 697.04157958254996 10
697.0415795826
afair, double has 13 decimal digits precision, so your
697.04157958254996 represented by another value. you just
Am Sonntag 23 August 2009 15:27:48 schrieb Steve:
On Sun, 2009-08-23 at 15:12 +0400, Eugene Kirpichov wrote:
There is *not* the same problem in Python:
$ python
Python 2.6.2 (r262:71600, Jul 9 2009, 23:16:53)
[GCC 4.4.0 20090506 (Red Hat 4.4.0-4)] on linux2
Type help, copyright,
2009/8/22 Roberto López plasterm...@hotmail.com:
If 4.0 / 2.0 was 1.98, it would be ok?
I think yes. However, hardware can afford to do computations as
accurately as possible, whereas software like Haskell Prelude can't.
The real value of log10 1000 is 3 (3.0). It can be
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