Exponential fit on both gnumeric and openoffice-calc are flawed for small values.

Reported by jacobfe on 2010-06-28
This bug affects 1 person
Affects Status Importance Assigned to Milestone
libio-digest-perl (Ubuntu)

Bug Description

Description: Ubuntu 10.04 LTS
Release: 10.04
gnumeric:1.10.1-1ubuntu1 0
openoffice.org-calc:1:3.2.0-7ubuntu4.1 0

For bothe of these applications the exponential fit is broken. Using the following data plot
0.000568 0.22
0.001136 0.05
0.00170 0.02
0.000136 0.97
0.000329 0.42

Plot and add a trend-line. Make the trend-line exponential and you get a garbage fit. If you multiply column A by 4, the fit works. Multiply by 3 and it fails. It appears that the algorithm used for this type of trend-line is flawed and has limitations that do not occur in MS Excel.

priya (priyamtk) on 2010-07-01
affects: ubuntu → libio-digest-perl (Ubuntu)

Confirmed for gnumeric. I'll have a look at this issue.

Propagated upstream for gnumeric: https://bugzilla.gnome.org/show_bug.cgi?id=633735.

The fix is easy, will be in git within 5 minutes. It would have been fixed much earlier if I had been aware of it.

Awesome! Thanks for fixing!

On 11/01/10 16:07, Jean Bréfort wrote:
> Fixed in gnumeric git:
> http://git.gnome.org/browse/goffice/commit/?id=e1d5d12da829a672a77664ac027984805af13e2a
> Thanks for reporting.

I'd like to say that I don't understand how this bug was attributed to libio-digest-perl. Looks quite weird. I think such bugs should be first opened upstream, unless they are clearly packaging issues. I'll blog about that. OOo guys should probably informed so that they can fix it too.

To post a comment you must log in.
This report contains Public information  Edit
Everyone can see this information.

Other bug subscribers

Remote bug watches

Bug watches keep track of this bug in other bug trackers.