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whatys521
USA
2 Posts |
 Posted - 07/10/2014 : 5:47:50 PM
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Hi, I have a problem fitting my data into the script.Please help.
constants:
Ki=2.9E5
It=0.000008
Ht=0.000006
Im=3E5
Io=1.7E5
paprameters: Kg, H
The y-script I put in is:
A=Ki*Kg;
B=Ki+Kg+Ki*Kg*It+Ki*Kg*x-Ki*Kg*Ht;
C=1+Ki*It+Kg*x-(Ki+Kg)*Ht;
D=-Ht;
for (H= Ht, step=1;abs(step)>1E-15;H=H-step){
step=(a*H*H*H+b*H*H+c*H+d)/(3*a*H*H+2*b*H+c);};
y=It*(Io*Ki*H+Im)/(1+Ki*H);
the data:
x y
0 306845
5E-7 292093
1E-6 286623
2E-6 268303
4E-6 269794
6E-6 233164
8E-6 211536
1E-5 206473
1.2E-5 200672
1.4E-5 193292
1.6E-5 197140
1.8E-5 175681
2E-5 180442
the data could not fit into the equation at all. way off. However, the y-script is published and should be right.
Please help me, I am so not familiar with Origin.
Thank you
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jasonzhao
China
262 Posts |
Posted - 07/11/2014 : 01:09:47 AM
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Hello,
When performing Nonlinear fitting in Origin, we can use Origin C code to build a function. However, in this fitting function you provided, H varies with the For loop, so it cannot be considered to be a parameter;
In addition, a proper initial value for parameter Kg is needed.
Best regards,
Jason Zhao
OriginLab Tech Service |
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whatys521
USA
2 Posts |
Posted - 07/11/2014 : 1:17:16 PM
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Hi, Jason,
Thank you for your answer.
I am not familiar with Origin at all. if I remove the H from the parameter list. and the only parameter is Kg, which I want to get the value for.
Also, what is the difference between the origin C and the script. The paper i am referring has this script only.
Thank you
Wei |
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jasonzhao
China
262 Posts |
Posted - 07/14/2014 : 07:22:33 AM
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Hello Wei,
We can construct a function by clicking main menu: Tools> Fitting Function Builder, and select Function type in Function Type group. The user defined function can be built by using Origin C, LabTalk script, expression, and so on. Y-script is similar to LabTalk script when building a fitting function. Besides, in the script you provided, the initial value for parameter Kg is very important. Would you like to provide a proper range for Kg based on its meaning? This will be helpful for us to calculate the fitting results.
Best regards,
Jason Zhao
OriginLab Tech Service |
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Nonlinear curve fitting-please help