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Zoid
Germany
5 Posts |
 Posted - 06/22/2011 : 12:25:24 PM
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Hi, everybody!
I just found this verrry nice forum and wanted to ask you guys for some help. 
I have a bunch of x-ray spectra (characteristic + Bremsstrahlung) and I have the job to determine h (Planck´s constant) from my experimental data by making a linear fit to the linear part of my Bremsstrahlung-spectrum, determine the zero points and then calculate h by a given formula. I imported the datasets to Origin 8.5.1, plotted all (eight) spectra into one graph and then made a linear fit to each one.
Now, my problem is that I just can´t get Origin to plot both x- and y-errors onto my plot points. I´ve managed to get either x- OR y-error bars, but it doesn´t seem to work for both in one graph. What I learned through the help file is that I have to add to EACH y-column (rate of my Geiger-Müller-counter) its yEr-column, otherwise (so it seems) Origin will add y-error bars only to the first (or last) plot and not to all. So I took an educated guess and added to EACH x-column (goniometer angle) the corresponding xEr-column, but Origin won´t show x-error bars at all (even though I correctly assigned each column as x/y/xEr/yEr).
Can anyone help me out with this? Alternatively, I´d be glad if you know a tutorial or something like that in which one can learn how to plot multiple datasets into ONE graph with ALL x- and y-error bars and make a (linear) fit on each set/plot that takes into account the given x and y errors (which, in this case, are constant).
Thanks a lot in advance, I hope my descriptions aren´t too confusing (I´m not a native English speaker).
Kindest regards,
Manfred |
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Hideo Fujii
USA
1582 Posts |
Posted - 06/22/2011 : 4:12:59 PM
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Hi Manfred,
I couldn't reproduce your difficulty to make a single graph with multiple plots with both X- and Y-error bars. I have organized a worksheet with two sets of curve data - X/Y/XErr/YErr/X/Y/XErr/YErr, highlighted all columns (though typical column order is X/XErr/Y/YErr), and made a plot. You see the sample in the screenshot below:
Maybe you can clarify the procedure you have tried.
--Hideo Fujii
OriginLab |
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Zoid
Germany
5 Posts |
Posted - 06/29/2011 : 12:19:17 PM
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Hi Hideo Fujii,
thanks a lot for the reply. I think the problem is to get those X- and Y-error bars in a plot comprising multiple data points where you have performed a (multiple) linear fit with X-error. One of the peculiarities I´ve encountered is that when you have multiple datasets in a workbook (X1/XErr1/Y1/YErr1, X2/XErr2/Y2/YErr2, ...) Origin often seems to disregard/leave the X-error range for the last dataset blank (in the fit menu), so I have to fill it in manually OR I sometimes have to solve the problem by finishing the fit and then opening Graph -> Plot Setup and adding the X-error bars manually by marking the respective "X" and "XErr" in the table/overview.
Another thing is that when you make multiple linear fits with X-error sometimes some of the fit curves are totally displaced, i.e. they have the right slope but the Y-intercept is way off...
Best regards,
Manfred |
Edited by - Zoid on 06/29/2011 12:19:53 PM |
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Zoid
Germany
5 Posts |
Posted - 06/29/2011 : 12:32:06 PM
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...my collegue also just pointed out that Origin might not tolerate
1.) working with different numbers of X-data points in one plot/fit,
2.) working with different magnitudes of X-errors in one plot/fit. |
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Hideo Fujii
USA
1582 Posts |
Posted - 06/29/2011 : 2:40:58 PM
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Hi Manfred,
I have tried a sample graph which contains two plots, and each of them has both YErr and XErr; Then, fitting with them simultaneously (as independent) worked fine with correct input assignments. The numbers of X data points or X errors shouldn't matter to do that if I understand correctly. Maybe you can send your Origin project file with the description of your procedure to Origin Technical Support (tech@originlab.com) referring to this post.
Best,
--Hideo Fujii
OriginLab |
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Multiple Fit Curves in 1 Diagram + X-&Y-Error Bars