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merrick
Portugal
2 Posts |
 Posted - 04/01/2015 : 11:19:51 AM
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I'm trying to created a new (user-defined) Non-Linear Curve Fit function to fit my experimental values based on the exchange equations by Johnson.
I simulated in excel (using solver and an approximation) and got a good agreement, however as soon as i used this simulated values in origin the fir goes completely crazy. There is no compilation error, so I assume the user-defined function is working well.
Can anyone help me?
My origin code is:
ouble pb,kb,s,l,z,Ma,Mb;
pb=1-pa;
kb=ka*pa/(1-pa);
s=0,5*(ka+kb+Da*x+Db*x);
l=0,5*(ka-kb+Da*x-Db*x);
z=sqrt((l^2)+ka*kb);
Ma=(0,5*pa-((l*pa-kb*pb)/(2*z)))*exp((-s+z)*T)+(0,5*pa+((l*pa-kb*pb)/(2*z)))*exp((-s-z)*T);
Mb=(0,5*pb+((l*pb-ka*pa)/(2*z)))*exp((-s+z)*T)+(0,5*pb-((l*pb-ka*pa)/(2*z)))*exp((-s-z)*T);
y=Ma+Mb
Thanks
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Shirley_GZ
China
Posts |
Posted - 04/02/2015 : 06:01:21 AM
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Hi,
It seems you didn’t define the parameter “ka” and “pa”. Would you please send us the FDF file (fitting function definition file) via tech@originlab.com and quote this post?
Thanks,
Originlab Technical Service Team |
Edited by - Shirley_GZ on 04/02/2015 06:04:43 AM |
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help!! Diffusion equations