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dybdal
Denmark
3 Posts |
 Posted - 12/04/2002 : 04:54:52 AM
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For the past four months, I have been trying to use Origin to fit some experimental data curves to an equation like the one presented below:
Y=1/v*H*exp(E/R(1/Tu-1/T))*exp(-1/v*integral(exp(E/R(1/Tu-1/T)))dT)
My X data are the T-values. The following parameters are constants: v, R and the fitting parameters I would like to determine are H, E, Tu.
I have my X data in Data1_A and my Y data in Data1_B.
Below I have listed my FDF file:
Brief Description=Integral function
Function Source=N/A
Function Type=User-Defined
Function Form=Y-Script
Number Of Parameters=3
Number Of Independent Variables=1
Number Of Dependent Variables=1
[FITTING PARAMETERS]
Naming Method=User-Defined
Names=E, Tu, H
Meanings=E (cal/mol), Tu (Kelvin), H (cal/mol)
Initial Values=90000(V),90(V),600000(V)
Lower Bounds=0(X, On),--(X, Off),--(X, Off)
Upper Bounds=--(X, Off),--(X, Off),--(X, Off)
Number Of Significant Digits=6,6,6
[FORMULA]
Data1_C=exp((E/R)*(1/Tu-1/Data1_A));
integrate Data1_C;
Data1_D=H*Data1_C*(1/v)*exp((-1/v)*(_integ_area));
Y=Data1_D(X);
[CONSTRAINTS]
/*Enter general linear constraints here*/
[CONSTANTS]
R=1.987
v=1.5
[INITIALIZATIONS]
/*Scripts to be executed before fitting, a good place for complicated initialization.*/
[AFTER FITTING]
/*Scripts to be executed after fitting, a good place for generating results.*/
[INDEPENDENT VARIABLES]
x=
[DEPENDENT VARIABLES]
y=
[CONTROLS]
General Linear Constraints=Off
Initialization Scripts=Off
Scripts After Fitting=Off
Number Of Duplicates=N/A
Duplicate Offset=N/A
Duplicate Unit=N/A
Generate Curves After Fitting=Yes
Curve Point Spacing=Same X as Fitting Data
Generate Peaks After Fitting=No
Generate Peaks During Fitting=No
Generate Peaks with Baseline=No
Paste Parameters to Plot After Fitting=Yes
Paste Parameters to Notes Window After Fitting=Yes
Generate Residue After Fitting=No
Keep Parameters=Yes
My problem is that I cant get my Y-script to work and every time I try to fit my data I get an error message. To solve my problems I read the notes regarding integrals from the Origin knowledge base on your website. But the suggestions did not solve problem and then I tried to find help in Origin forums but without any luck.
Recently I upgraded from Origin 5.0 to 7.0 but I still have not solved problem.
I would very much appreciate if anyone could help to find a solution to my problem.
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easwar
USA
1964 Posts |
Posted - 12/04/2002 : 12:28:31 PM
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Hello,
What is the error message that you get? I copy-pasted and created an FDF from what you posted here and the error message I get is: "System variables X,Y,Z...E..cannot be used...". I notice that you are using E as a parameter, and E is a reserved name. Is that the error you get?
You should send your FDF and an OPJ with data to tech support.
Easwar
OriginLab. |
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Fitting problems