[LabPlot2] [Bug 386800] Custom fitting often fails

[Uwe Stöhr]

https://bugs.kde.org/show_bug.cgi?id=386800

--- Comment #26 from Uwe Stöhr  ---
> I will put this on the TODO list for the next release

Many thanks. I opened bug 394223 as feature request.

> Is it ok to contact you when we think this new feature is working?

Sure. You have already my private mail address.

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[LabPlot2] [Bug 386800] Custom fitting often fails

[Stefan Gerlach]

https://bugs.kde.org/show_bug.cgi?id=386800

Stefan Gerlach  changed:

   What|Removed |Added

 Resolution|--- |FIXED
 Status|CONFIRMED   |RESOLVED

--- Comment #25 from Stefan Gerlach  ---
It looks like custom fitting in LabPlot now works. Supporting a preview of the
fitting curve using the start values is a new feature which currently is
breaking too many things (just before the release of 2.5). But i  will put this
on the TODO list for the next release and hope to make it possible soon. Is it
ok to contact you when we think this new feature is working?

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[LabPlot2] [Bug 386800] Custom fitting often fails

[Uwe Stöhr]

https://bugs.kde.org/show_bug.cgi?id=386800

--- Comment #24 from Uwe Stöhr  ---
As I wrote in comment 22: "the fitting result are now correct but as long as
LabPlot does not draw the fit curve with the given start parameters, the
problem is not fixed in my opinion."

> does MagicPlot Pro find the "correct" parameter values when the starting 
> values are 1,1,1? If it is, then it's almost magic

Well, it is called MagicPlot ;-) No, it does not find the optimal fit result
with these parameters. it finds this:
https://bugsfiles.kde.org/attachment.cgi?id=108821

The reason this bug is now still open is that LabPlot does not give feedback
about the fit curve. So if I use 1,1,1 as start parameter it is very important
that LabPlot drawn immediately the function
exp(sin(x))+1
into the plot. Then the user gets a feeling if his start parameters are
sensible.

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[LabPlot2] [Bug 386800] Custom fitting often fails

[bugzilla_noreply]

https://bugs.kde.org/show_bug.cgi?id=386800

--- Comment #23 from urcind...@gmail.com ---
Created attachment 112528
  --> https://bugs.kde.org/attachment.cgi?id=112528=edit
Test works OK in Linux

Well, I just sync'ed and compiled labplot again (Gentoo Linux). My results are
identical to those shown by Uwe Stöhr in his MagicPlot Pro graph after knowing
the parameters value range, as I show in the new attached file. So, I think
there's really no issue here and labplot is now perfectly able to perform the
suggested fitting.

I got a question for Uwe: does MagicPlot Pro find the "correct" parameter
values when the starting values are 1,1,1? If it is, then it's almost magic,
imho. The function is complexed and, in these cases, it is common for whatever
fitting algorithm that, the further from a straight line the function is, the
more prone to fail is the fit when the initial guess values are far away from
the true ones.

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[LabPlot2] [Bug 386800] Custom fitting often fails

[Uwe Stöhr]

https://bugs.kde.org/show_bug.cgi?id=386800

Uwe Stöhr  changed:

   What|Removed |Added

 Resolution|WORKSFORME  |---
 Status|NEEDSINFO   |CONFIRMED

--- Comment #22 from Uwe Stöhr  ---
> The parameter a is very sensitive. The fit works for me using start values 
> closer to the result (b=2, a=.05, c=2).

;-) Well, people use LabPlot because they don't yet the solution. using 1 for
all 3 parameters is sensible because one can expect that the solution will have
positive values and that b and c won't be very high.

However, I restarted now from scratch using RC17 and this recipe:

- create a new table with 2 columns
- fill the table columns with row numbers
- create a new custom fit
- use as fit function this one
exp(b*sin(a*x))+c
- set fit interval x:10 - 25
- set as start value for all parameters "1"

result: one doesn't get a fit curve

What is missing is that LabPlot does not draw the cureve for A=b=c=1
immediately, meaning even before starting the calculation of the fit. Other
programs like MagicPlot do this since it helps a lot to see if the start
parameters are sensible.

With RC17 the fitting result are now correct but as long as LabPlot does not
draw the fit curve with the given start parameters, the problem is not fixed in
my opinion.

Btw. with RC17 LabPlot does no longer show any fit curve. I'll open new bug
reports now.

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[LabPlot2] [Bug 386800] Custom fitting often fails

[Stefan Gerlach]

https://bugs.kde.org/show_bug.cgi?id=386800

Stefan Gerlach  changed:

   What|Removed |Added

 Status|REOPENED|NEEDSINFO
 Resolution|--- |WORKSFORME

--- Comment #21 from Stefan Gerlach  ---
I uploaded a new Windows packages including the latest fixes at
https://theorie.physik.uni-konstanz.de/gerlach/labplot/labplot-2.5.0rc17-64bit-setup.exe
The parameter a is very sensitive. The fit works for me using start values
closer to the result (b=2, a=.05, c=2).

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[LabPlot2] [Bug 386800] Custom fitting often fails

[Uwe Stöhr]

https://bugs.kde.org/show_bug.cgi?id=386800

Uwe Stöhr  changed:

   What|Removed |Added

 Resolution|FIXED   |---
 Status|RESOLVED|REOPENED

--- Comment #20 from Uwe Stöhr  ---
This bug is not fixed in the latest available LabPlot version.

> If you can provide the information requested in comment #14, please add it.
OK:

> Which values for a,b,c do you expect for best fitting you data?
See the screen shot I once attached with a correct fit:
https://bugsfiles.kde.org/attachment.cgi?id=108823

> the data columns are not restored when opening your project. What happens 
> when  you select the x- and y-column correctly?
I don't know what you mean. I created the file using LabPlot so there must be
another bug that columns are not restored.

Is there a new LabPlot build available to test?

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[LabPlot2] [Bug 386800] Custom fitting often fails

[Stefan Gerlach]

https://bugs.kde.org/show_bug.cgi?id=386800

Stefan Gerlach  changed:

   What|Removed |Added

 Resolution|--- |FIXED
 Status|CONFIRMED   |RESOLVED

--- Comment #19 from Stefan Gerlach  ---
Both problems from comment #18 are fixed now. Please try again to check if
there is still anything left to be improved.

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[LabPlot2] [Bug 386800] Custom fitting often fails

[Stefan Gerlach]

https://bugs.kde.org/show_bug.cgi?id=386800

Stefan Gerlach  changed:

   What|Removed |Added

 Status|NEEDSINFO   |CONFIRMED
 Resolution|WAITINGFORINFO  |---
 Ever confirmed|0   |1

--- Comment #18 from Stefan Gerlach  ---
I see at least two things that can be improved. The default ranges should be
not 0..0  and "Apply" should not be possible with start values outside the
given range. I will fix these soon.

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[LabPlot2] [Bug 386800] Custom fitting often fails

[bugzilla_noreply]

https://bugs.kde.org/show_bug.cgi?id=386800

urcind...@gmail.com changed:

   What|Removed |Added

 CC||urcind...@gmail.com

--- Comment #17 from urcind...@gmail.com ---
Created attachment 112508
  --> https://bugs.kde.org/attachment.cgi?id=112508=edit
test as described by OP

I'm not the original poster, but I tried what he suggests in the opening
message with a recent compilation, a few minutes ago:
===
GIT update -->
   repository:   https://anongit.kde.org/labplot
   updating from commit: 9ba9b2636a94ec4c53dba369c922cb5b482c8333
   to commit:ed4021f2e459ab4cbc8ff4ff5a9c7b2d5c908924
===

My findings:
1) When entering the parameter initial values, b fields turn red when entering
1. However, it is accepted: after pressing "Apply" and entering into Options
again, b=1 is there and b fields are no longer red.

2) The reason for it to turn red is both b and a have default lower and upper
limits equal to 0, whilst you are telling labplot their value is 1.

3) If you then perform the fitting, c=1 and both a and b get the same huge
value: ~1.8e308

4) However, if you change the default 0 for both lower and upper limits (bug?)
to none, set the starting value to 1 for the three parameters and perform the
fitting, then you get distinct values for them. The fitting is not good, as you
can see in the attached file, because probably you would need to set more
realistic starting values, but I would say this is a normal behavior for such a
function.

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[LabPlot2] [Bug 386800] Custom fitting often fails

[Christoph Feck]

https://bugs.kde.org/show_bug.cgi?id=386800

--- Comment #16 from Christoph Feck  ---
To further investigate this issue, LabPlot developers need the information
requested in comment #14. If you can provide it, or need help with finding that
information, please add a comment.

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[LabPlot2] [Bug 386800] Custom fitting often fails

[Christoph Feck]

https://bugs.kde.org/show_bug.cgi?id=386800

--- Comment #15 from Christoph Feck  ---
If you can provide the information requested in comment #14, please add it.

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[LabPlot2] [Bug 386800] Custom fitting often fails

[Stefan Gerlach]

https://bugs.kde.org/show_bug.cgi?id=386800

Stefan Gerlach  changed:

   What|Removed |Added

 Resolution|--- |WAITINGFORINFO
 Status|UNCONFIRMED |NEEDSINFO

--- Comment #14 from Stefan Gerlach  ---
the data columns are not restored when opening your project. What happens when 
you select the x- and y-column correctly?
The fit parameter are using lower and upper limits for the values. Which values
for a,b,c do you expect for best fitting you data?

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[LabPlot2] [Bug 386800] Custom fitting often fails

[Uwe Stöhr]

https://bugs.kde.org/show_bug.cgi?id=386800

--- Comment #13 from Uwe Stöhr  ---
Created attachment 110551
  --> https://bugs.kde.org/attachment.cgi?id=110551=edit
.lml test file

Test file for comment 12

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[LabPlot2] [Bug 386800] Custom fitting often fails

[Uwe Stöhr]

https://bugs.kde.org/show_bug.cgi?id=386800

Uwe Stöhr  changed:

   What|Removed |Added

 Status|NEEDSINFO   |UNCONFIRMED
 Resolution|WAITINGFORINFO  |---

--- Comment #12 from Uwe Stöhr  ---
(In reply to Stefan Gerlach from comment #11)
> Do this problem still exist in the latest version 2.5rc8?

Yes. When opening the attached .lml file I still get both errors:

> 1. the fit parameter b gets red, see attached
> 2. one cannot see the fit functions using the given parameters. Therefore one 
> doesn't know is the parameter "1" is sensible.

Additionally:

3. The fit parameter window can still not be moved.
4. I cannot press the recalculate button because it is permanently grayed-out.

If I therefore create a new fit to be able to calculate I still get senseless
results.

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[LabPlot2] [Bug 386800] Custom fitting often fails

[Stefan Gerlach]

https://bugs.kde.org/show_bug.cgi?id=386800

Stefan Gerlach  changed:

   What|Removed |Added

 Resolution|--- |WAITINGFORINFO
 Status|UNCONFIRMED |NEEDSINFO

--- Comment #11 from Stefan Gerlach  ---
Do this problem still exist in the latest version 2.5rc8?

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[LabPlot2] [Bug 386800] Custom fitting often fails

[Uwe Stöhr]

https://bugs.kde.org/show_bug.cgi?id=386800

--- Comment #10 from Uwe Stöhr  ---
Created attachment 109438
  --> https://bugs.kde.org/attachment.cgi?id=109438=edit
another test file

with this test file the Recalculate button is always disabled

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[LabPlot2] [Bug 386800] Custom fitting often fails

[Uwe Stöhr]

https://bugs.kde.org/show_bug.cgi?id=386800

--- Comment #9 from Uwe Stöhr  ---
Created attachment 109437
  --> https://bugs.kde.org/attachment.cgi?id=109437=edit
lml testfile

test project showing the bug

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[LabPlot2] [Bug 386800] Custom fitting often fails

[Uwe Stöhr]

https://bugs.kde.org/show_bug.cgi?id=386800

Uwe Stöhr  changed:

   What|Removed |Added

 Resolution|WORKSFORME  |---
 Status|RESOLVED|UNCONFIRMED

--- Comment #8 from Uwe Stöhr  ---
> I uploaded a new package

The bug persists for me, with your build and also with mine. Attached is my
test file.

The situation is now worse: The recalculate button is always disabled as you
can see in my test file. In order to get a fit I have to create a new fit plot.

-> major regression

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[LabPlot2] [Bug 386800] Custom fitting often fails

[Stefan Gerlach]

https://bugs.kde.org/show_bug.cgi?id=386800

Stefan Gerlach  changed:

   What|Removed |Added

 Resolution|--- |WORKSFORME
 Status|UNCONFIRMED |RESOLVED

--- Comment #7 from Stefan Gerlach  ---
I uploaded a new package at
https://theorie.physik.uni-konstanz.de/gerlach/labplot/labplot-2.5.0rc4-64bit-setup.exe

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[LabPlot2] [Bug 386800] Custom fitting often fails

[Stefan Gerlach]

https://bugs.kde.org/show_bug.cgi?id=386800

Stefan Gerlach  changed:

   What|Removed |Added

   Assignee|alexander.se...@web.de  |stefan.gerlach@uni-konstanz
   ||.de

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[LabPlot2] [Bug 386800] Custom fitting often fails

[Uwe Stöhr]

https://bugs.kde.org/show_bug.cgi?id=386800

--- Comment #6 from Uwe Stöhr  ---
> I could not reproduce the problem. Attached my screenshot of your test case. 
> Is there anything i may have missed?

Then this bug was fixed in the meantime. I use the same settings as you and
"0.01" as start value for the parameter a, 1 for b and c. As result i get what
I posted:
https://bugsfiles.kde.org/attachment.cgi?id=108819

To be able to check if this bug is fixed, I need a new build from you.

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[LabPlot2] [Bug 386800] Custom fitting often fails

[Stefan Gerlach]

https://bugs.kde.org/show_bug.cgi?id=386800

Stefan Gerlach  changed:

   What|Removed |Added

 CC||stefan.gerlach@uni-konstanz
   ||.de

--- Comment #5 from Stefan Gerlach  ---
Created attachment 108942
  --> https://bugs.kde.org/attachment.cgi?id=108942=edit
screenshot of test case

I could not reproduce the problem. Attached my screenshot of your test case. Is
there anything i may have missed?

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[LabPlot2] [Bug 386800] Custom fitting often fails

[bugzilla_noreply]

https://bugs.kde.org/show_bug.cgi?id=386800

--- Comment #4 from uwesto...@web.de ---
Created attachment 108823
  --> https://bugs.kde.org/attachment.cgi?id=108823=edit
MagicPlot good fit result with a=0.01

I attached is the fit result of MagicPlot using the start parameters a=0.01,
b=1 and c=1.

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[LabPlot2] [Bug 386800] Custom fitting often fails

[bugzilla_noreply]

https://bugs.kde.org/show_bug.cgi?id=386800

uwesto...@web.de changed:

   What|Removed |Added

   Severity|normal  |major

--- Comment #3 from uwesto...@web.de ---
OK, let's assume the user got the idea that the parameter a has to be a low
value despite LP doesn't show him the fit function.

- Therefore let's fit with the parameters
a: "0.01", b and c with "1"

result: still not fit. So the fit routine in LP seems to have an error because
doing the same with MagicPlot leads to a nice fit result, see attached.

now it gets even worse:

- now use again
a: "0.01", b and c with "1"
but this time set a to be fixed.

result: one gets for the parameter a the value 1.79769e+308 although it was set
fixed and must not be changed during the fit.

I played a  bit with fitting and because of this bug LP is not usable for me
regarding custom fits.

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[LabPlot2] [Bug 386800] Custom fitting often fails

[bugzilla_noreply]

https://bugs.kde.org/show_bug.cgi?id=386800

--- Comment #2 from uwesto...@web.de ---
Created attachment 108821
  --> https://bugs.kde.org/attachment.cgi?id=108821=edit
Fit result from MagicPlot

The fit is bad but at least is exists and one can see it. One gets the idea
that setting parameter a to a low value should result in a good fit.

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[LabPlot2] [Bug 386800] Custom fitting often fails

[bugzilla_noreply]

https://bugs.kde.org/show_bug.cgi?id=386800

--- Comment #1 from uwesto...@web.de ---
Created attachment 108819
  --> https://bugs.kde.org/attachment.cgi?id=108819=edit
no fit result and senseless fit parameters

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