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lvdt
Austria
4 Posts |
 Posted - 11/10/2020 : 12:02:09 PM
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Hello,
i've been searching on how to do this all day and i couldn't find anything.
This is a picture of what i want to do:
https://my.originlab.com/ftp/forum_and_kbase/Images/whatiwanttodo.jpg
i have to do 2 linear regressions on the linear parts of the curve. I know how to do that. However, i don't know how i can extend the regression curve. next i need to calculate the area between the 2 regression curves and my original curve. then i need to find the x value where the 2 areas are exactly the same, so i can calculate the values of the 2 regression curves at that x value.
I hope i explained it well.
Thanks,
Lorenz |
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YimingChen
1592 Posts |
Posted - 11/10/2020 : 2:33:32 PM
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Hi,
1. In Linear Regression Dialog, you can set Fitted Curve range.
2. You can use Integrate Gadget to obtain the integral curves of your data to the two baselines (linear fitted curve). With some math, you should be getting the two areas as a function of x value. Plot them on same graph, and Use the intersect gadget to get the x value. See below:
James |
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lvdt
Austria
4 Posts |
Posted - 11/11/2020 : 04:51:25 AM
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Hey,
thanks a lot for your help! i appreciate it very much!
I have some problems using the integration tool. I cannot select any of my regression curves as baselines, nor can i integrate my upper regression curve using my dataset as baseline. the only options i have available to use as baseline are (roughly translated from german to english):
1. none (Y=0)
2. constant y
3. straight line (not the right option)
4. use existing dataset
5. second differentiation
6. weighted endpoints
Is there a way to get the integrated function of my dataset? Then i could do this oldschool with pen and paper.
Thank you very much for your help!
Lorenz
PS.: I use OriginPro 2016 as this is the version my Uni offers a license for. |
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lvdt
Austria
4 Posts |
Posted - 11/11/2020 : 09:15:57 AM
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okay, i figured out how to use the regression curve as baseline. But as i still don't know how to get the integral function of my dataset i had to manually change the integration boundary until the areas were the same. it was tedious but it worked eventually.
if you have the time and don't mind it, i would very much appreciate it if you show me how i could do this automatically the next time.
Thanks,
Lorenz |
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YimingChen
1592 Posts |
Posted - 11/11/2020 : 3:07:05 PM
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Hi,
In Integrate Gadget, there is a check box allowing you to generate integral curve. See below:
James |
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lvdt
Austria
4 Posts |
Posted - 11/12/2020 : 11:43:09 AM
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Hey,
this doesn't display anything. Doesn' matter which output i choose, it just doesn't change a thing. Thanks anyways!
Lorenz |
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YimingChen
1592 Posts |
Posted - 11/12/2020 : 1:32:57 PM
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You need to click the triangular button to the upper right of the ROI box (Yellow), and select New Output to get the integral curve data.
James |
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Topic |
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point at which area under curve is halved