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lr23919
USA
6 Posts |
 Posted - 09/26/2018 : 10:56:07 PM
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Origin Ver. and Service Release (Select Help-->About Origin):
Operating System: Hello, I have some sigmoidal curves from the amyloid formation kinetics, that I need to use this equation to find lag time, and growth rate:
y=y0+A/(1+exp(-k*(t-t0.5)))
y0=pre-transition baseline
A=amplitude of transition
k=apparent growth rate
t0.5=midpoint
tlag=t0.5-1/2k
I don't know how to write the equation in origin to fit my data. I'm using Origin 8. I'm stuck,please help. |
Edited by - lr23919 on 09/26/2018 11:03:58 PM |
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yuki_wu
896 Posts |
Posted - 09/26/2018 : 11:29:46 PM
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Hi,
Please take a look at this tutorial. The tutorial will show you how to define a fitting function:
https://www.originlab.com/doc/Tutorials/UserDef-FitFunc
However, your Origin is too old, not sure if it works. You better upgrade to our latest version, Origin 2018b.
Regards,
Yuki
OriginLab
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lr23919
USA
6 Posts |
Posted - 09/26/2018 : 11:46:55 PM
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I do have the latest version, I meant 2018b by saying origin 8.
I did look at the guides, watched videos but I'm still confused and stuck.
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lr23919
USA
6 Posts |
Posted - 09/26/2018 : 11:51:27 PM
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| How would you write this equation on origin? would you change t to x and t0.5 to x0.5? or k to x? |
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lr23919
USA
6 Posts |
Posted - 09/26/2018 : 11:54:01 PM
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| What type of function is this? Expression? Equation? ORigin C? |
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yuki_wu
896 Posts |
Posted - 09/27/2018 : 01:45:37 AM
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Hi,
Expression is okay.
For x or t, this depends on the independent variable you define. You should really take a few minutes to read that tutorial.
Regards,
Yuki
OriginLab |
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lr23919
USA
6 Posts |
Posted - 09/27/2018 : 2:04:26 PM
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| Thank you, I appreciate your help. |
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Need help on user defined function builder ASAP!