* adding up decimal fractions in the spreadsheet
@ 2008-09-27 7:19 Rainer Thiel
2008-09-27 12:19 ` Carsten Dominik
2008-09-27 13:21 ` Manish
0 siblings, 2 replies; 7+ messages in thread
From: Rainer Thiel @ 2008-09-27 7:19 UTC (permalink / raw)
To: emacs-orgmode
Following a hint by Bernt Hansen, I have now changed org-table-sum to
(format "%s" res) until I'll be able to use the corrected version
Carsten Dominik uploaded to the git repository (which I am not sure
how to access).
Even so, org-table-sum at times shows a strange behaviour.
When I try to sum up the following table:
| 12130.68 |
| -1444.19 |
| -12744.90 |
| -186.00 |
| 7000.00 |
| -7056.00 |
| -335.58 |
| -277.00 |
I get -2912.9899999999993 (-2912.99 being the exact result). This is
something I'd expect when square roots or logarithms are implied, but
with such a simple addition and subtraction of decimal numbers I'd be
inclined to call it a bug. Is there a way to improve org-mode in this
respect?
Many thanks again for this great mode
--
Prof. Dr. Rainer Thiel
Institut für Altertumswissenschaften
07737 Jena, Germany (EU)
r.thiel@uni-jena.de
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: adding up decimal fractions in the spreadsheet
2008-09-27 7:19 adding up decimal fractions in the spreadsheet Rainer Thiel
@ 2008-09-27 12:19 ` Carsten Dominik
[not found] ` <d6b6c7740809270606p679feb82n6fbe5f4d582ebcfa@mail.gmail.com>
2008-09-27 13:21 ` Manish
1 sibling, 1 reply; 7+ messages in thread
From: Carsten Dominik @ 2008-09-27 12:19 UTC (permalink / raw)
To: r.thiel; +Cc: emacs-orgmode
Hi Rainer,
it is a common mis-conception that a number that has a limited number
of digits in base 10 can be represented exactly on a computer. This
is correct for integers, but not for fractional numbers.
Example:
1. Open the emacs calc with M-x calc RET
2. Type 12130.68 (first number from your example)
3. Press `p 200 RET' to switch to 200 digit precision.
4. press `d r 2 RET' o display the number in Base 2.
You'll see
10111101100010.1010111000010100011110101110000101000111101011100001010001111010111000010100011110101110000101000111101011100001010001111010111000010100011110101110000
................
It works the other way round as well, for example
0.33333333............. has an exact representation in base 3 (0.1).
This means that even simple additions like this do produce small
errors on computers, and the displayed result will depend upon how he
conversion is done.
(format "%s" x) just spits out digits, as many as possible. That is
why the fix I have pushed to the git repo uses
(number-to-string res)
and not
(format "%s" res)
number-to-string is an internal function that tries very hard to do
the conversion in the way you intend it.
- Carsten
On Sep 27, 2008, at 9:19 AM, Rainer Thiel wrote:
> Following a hint by Bernt Hansen, I have now changed org-table-sum to
> (format "%s" res) until I'll be able to use the corrected version
> Carsten Dominik uploaded to the git repository (which I am not sure
> how to access).
>
> Even so, org-table-sum at times shows a strange behaviour.
>
> When I try to sum up the following table:
>
> | 12130.68 |
> | -1444.19 |
> | -12744.90 |
> | -186.00 |
> | 7000.00 |
> | -7056.00 |
> | -335.58 |
> | -277.00 |
>
> I get -2912.9899999999993 (-2912.99 being the exact result). This is
> something I'd expect when square roots or logarithms are implied, but
> with such a simple addition and subtraction of decimal numbers I'd be
> inclined to call it a bug. Is there a way to improve org-mode in this
> respect?
>
> Many thanks again for this great mode
> --
> Prof. Dr. Rainer Thiel
> Institut für Altertumswissenschaften
> 07737 Jena, Germany (EU)
> r.thiel@uni-jena.de
>
>
> _______________________________________________
> Emacs-orgmode mailing list
> Remember: use `Reply All' to send replies to the list.
> Emacs-orgmode@gnu.org
> http://lists.gnu.org/mailman/listinfo/emacs-orgmode
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: adding up decimal fractions in the spreadsheet
2008-09-27 7:19 adding up decimal fractions in the spreadsheet Rainer Thiel
2008-09-27 12:19 ` Carsten Dominik
@ 2008-09-27 13:21 ` Manish
2008-09-27 13:29 ` Rainer Thiel
1 sibling, 1 reply; 7+ messages in thread
From: Manish @ 2008-09-27 13:21 UTC (permalink / raw)
To: r.thiel; +Cc: emacs-orgmode
On Sat, Sep 27, 2008 at 12:49 PM, Rainer Thiel <wrote:
> Following a hint by Bernt Hansen, I have now changed org-table-sum to
> (format "%s" res) until I'll be able to use the corrected version
> Carsten Dominik uploaded to the git repository (which I am not sure
> how to access).
About not being sure how to access latest Org, FAQ at
http://orgmode.org/worg/org-faq.php might help.
-- Manish
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: adding up decimal fractions in the spreadsheet
2008-09-27 13:21 ` Manish
@ 2008-09-27 13:29 ` Rainer Thiel
2008-09-29 2:46 ` Manish
0 siblings, 1 reply; 7+ messages in thread
From: Rainer Thiel @ 2008-09-27 13:29 UTC (permalink / raw)
To: Manish, emacs-orgmode
2008/9/27 Manish <mailtomanish.sharma@gmail.com>:
> About not being sure how to access latest Org, FAQ at
> http://orgmode.org/worg/org-faq.php might help.
Thank you, Manish. Is this lykely to work on a Windows machine with
cygwin installed, too?
Best wishes, and many thanks again,
Rainer
--
Prof. Dr. Rainer Thiel
Institut für Altertumswissenschaften
07737 Jena, Germany (EU)
r.thiel@uni-jena.de
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: adding up decimal fractions in the spreadsheet
[not found] ` <B1260157-B3E5-4704-8739-F4718BDFCAEC@uva.nl>
@ 2008-09-27 14:20 ` Rainer Thiel
2008-09-27 17:59 ` Carsten Dominik
0 siblings, 1 reply; 7+ messages in thread
From: Rainer Thiel @ 2008-09-27 14:20 UTC (permalink / raw)
To: Carsten Dominik, emacs-orgmode
Hi Carsten,
2008/9/27 Carsten Dominik <dominik@uva.nl>:
> The other thing you can do is to use your own format to convert the number.
> Maybe something like "%.2f" will work for you? Hard to make this correct
> for the general case though.
Yes, this is not a way to go, as far as I can see, for exactly that reason.
Interestingly,
| 12130.68 |
| -1444.19 |
| -12744.90 |
| -186.00 |
| 7000.00 |
| -7056.00 |
| -335.58 |
| -277.00 |
| -2912.99 |
#+TBLFM: @9$1=@1$1+@2$1+@3$1+@4$1+@5$1+@6$1+@7$1+@8$1
gives the correct value, there's no need to add `;f2' at the end of
the last line. This in itself is a way to go, of course, but would be
more comfortable to have a way to sum up all rows but the last one
(without having to keep track of the number of rows) or at least to
work with ranges, which as far as I have seen so far seems not to be
possible in this case.
These are minutiae, of course. org-mode is already excellent, and
since I discovered it a few weeks ago, I've been making use of it at
all times.
Many thanks again,
Rainer
--
Prof. Dr. Rainer Thiel
Institut für Altertumswissenschaften
07737 Jena, Germany (EU)
r.thiel@uni-jena.de
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: adding up decimal fractions in the spreadsheet
2008-09-27 14:20 ` Rainer Thiel
@ 2008-09-27 17:59 ` Carsten Dominik
0 siblings, 0 replies; 7+ messages in thread
From: Carsten Dominik @ 2008-09-27 17:59 UTC (permalink / raw)
To: r.thiel; +Cc: emacs-orgmode
Hi Rainer,
On Sep 27, 2008, at 4:20 PM, Rainer Thiel wrote:
> Hi Carsten,
>
> 2008/9/27 Carsten Dominik <dominik@uva.nl>:
>> The other thing you can do is to use your own format to convert the
>> number.
>> Maybe something like "%.2f" will work for you? Hard to make this
>> correct
>> for the general case though.
>
> Yes, this is not a way to go, as far as I can see, for exactly that
> reason.
I agree.
>
>
> Interestingly,
>
> | 12130.68 |
> | -1444.19 |
> | -12744.90 |
> | -186.00 |
> | 7000.00 |
> | -7056.00 |
> | -335.58 |
> | -277.00 |
> | -2912.99 |
> #+TBLFM: @9$1=@1$1+@2$1+@3$1+@4$1+@5$1+@6$1+@7$1+@8$1
>
> gives the correct value, there's no need to add `;f2' at the end of
> the last line.
Yes, calc has its own rules for formatting numbers
> This in itself is a way to go, of course, but would be
> more comfortable to have a way to sum up all rows but the last one
> (without having to keep track of the number of rows) or at least to
> work with ranges, which as far as I have seen so far seems not to be
> possible in this case.
Check out the manual section about the spreadsheet, and the
corresponding tutorial on worg. A lot can be done with that, and
there are ranges between row numbers or between horizontal lines. In
your example:
| 12130.68 |
| -1444.19 |
| -12744.90 |
| -186.00 |
| 7000.00 |
| -7056.00 |
| -335.58 |
| -277.00 |
| -2912.99 |
#+TBLFM: @9$1=vsum(@1..@8)
Or much better:
|-----------|
| 12130.68 |
| -1444.19 |
| -12744.90 |
| -186.00 |
| 7000.00 |
| -7056.00 |
| -335.58 |
| -277.00 |
|-----------|
| -2912.99 |
#+TBLFM: @9$1=vsum(@I..@II)
Add new line with M-S-down, so that the absolute reference to the last
row will automatically be shifted.
org-table-sum is an old hack, from before the existence of the
spreadsheet functions. I still use I, but only occasionally, not for
anything I need to change and recompute.
>
>
> These are minutiae, of course. org-mode is already excellent, and
> since I discovered it a few weeks ago, I've been making use of it at
> all times.
Good to know.
- Carsten
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: adding up decimal fractions in the spreadsheet
2008-09-27 13:29 ` Rainer Thiel
@ 2008-09-29 2:46 ` Manish
0 siblings, 0 replies; 7+ messages in thread
From: Manish @ 2008-09-29 2:46 UTC (permalink / raw)
To: r.thiel; +Cc: emacs-orgmode
On Sat, Sep 27, 2008 at 6:59 PM, Rainer Thiel wrote:
> 2008/9/27 Manish :
>> About not being sure how to access latest Org, FAQ at
>> http://orgmode.org/worg/org-faq.php might help.
>
> Thank you, Manish. Is this lykely to work on a Windows machine with
> cygwin installed, too?
Yes, I use this on Cygwin.
I just do not do `make install' and add `~/elisp/org-mode.git/lisp'
and `~/elisp/org-mode.git/contrib/lisp' to the load path (for ~ to
work I have HOME defined in Windows user environment variables.)
Updating Org then boils down to: git pull && make clean && make &&
make doc.
HTH,
-- Manish
^ permalink raw reply [flat|nested] 7+ messages in thread
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2008-09-27 7:19 adding up decimal fractions in the spreadsheet Rainer Thiel
2008-09-27 12:19 ` Carsten Dominik
[not found] ` <d6b6c7740809270606p679feb82n6fbe5f4d582ebcfa@mail.gmail.com>
[not found] ` <B1260157-B3E5-4704-8739-F4718BDFCAEC@uva.nl>
2008-09-27 14:20 ` Rainer Thiel
2008-09-27 17:59 ` Carsten Dominik
2008-09-27 13:21 ` Manish
2008-09-27 13:29 ` Rainer Thiel
2008-09-29 2:46 ` Manish
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