The Origin Forum
File Exchange
Try Origin for Free
The Origin Forum
Home | Profile | Register | Active Topics | Members | Search | FAQ | Send File to Tech support
Username:
Password:
Save Password
Forgot your Password? | Admin Options

 All Forums
 Origin Forum
 Origin Forum
 Modified Gompertz equation for Bio-Hydrogen
 New Topic  Reply to Topic
 Printer Friendly
Author Previous Topic Topic Next Topic Lock Topic Edit Topic Delete Topic New Topic Reply to Topic

Tejaswi

Germany
2 Posts

Posted - 04/14/2021 :  06:10:20 AM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Hello all,
I am trying to fit my experimental data of bio-H2 production into modified gompertz.

The equation I want to use is

y = H*exp(-exp(((H*2.718)/H)*(l-t)+1))

Here H is the maximu cumulative Hydrogen
Y is the amount of hydrogen that is calculated at a given time

I created a duplicate version of the existing gompertz equation and modified the C program.
I have "x" as independant variable and "y" as dependant variable. The parameters are H, R,l,t

When I try to fit the equation, it does not calculate the values of y when I check the report. It shows an error saying "Fit failed (-207)"

I tried making modifications in the program and it shows an error. Any help in regards to programming and fitting the datas is appreciated.

Thanks and Regards,
Tejaswi

AmandaLu

439 Posts

Posted - 04/14/2021 :  06:41:05 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi,

First of all, please make sure you defined the function correctly. For example, I don’t see a parameter “R” in the function you mentioned.

Secondly, "Fit failed (-207)" means “Fit did not converge, for some other unknown reason(s).”
https://www.originlab.com/doc/Origin-Help/NLFit-Result-FitStatusCode

You can refer to this page for a possible reason:
https://www.originlab.com/doc/Origin-Help/The_Reason_Why_Fail_to_Converge

Thanks,
Amanda
OriginLab Technical Service
Go to Top of Page

Tejaswi

Germany
2 Posts

Posted - 04/15/2021 :  1:19:43 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi,
I corrected the equation.
y=H*exp(-exp(((R*2.718)/H)*(l-t)+1))

and the C program I modified is :

sort( x_y_curve );
//smooth( x_y_curve, 2 );
H = max(y_data);
x_y_curve = ln( x_y_curve );
x_y_curve = ln( ln(H) - x_y_curve );
double coeff[2];
fitpoly( x_y_curve, 1, coeff );
R= -coeff[0] / coeff[1];
l = -coeff[1];

I am not sure how I can write a code to calculate the values of Y.

Regards,
Tejaswi.

Edited by - Tejaswi on 04/15/2021 3:31:14 PM
Go to Top of Page

AmandaLu

439 Posts

Posted - 04/20/2021 :  10:47:16 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi Tejaswi,

The OC code is used to calculate the initial values of parameters. Y doesn’t need a initial value to fit. If you want to fit Y with your defined function, you can select Analysis: Fitting: Nonlinear Curve Fit menu. In the dialog, select your defined function and fit your XY data.

Thanks,
Amanda
OriginLab Technical Service
Go to Top of Page
  Previous Topic Topic Next Topic Lock Topic Edit Topic Delete Topic New Topic Reply to Topic
 New Topic  Reply to Topic
 Printer Friendly
Jump To:
The Origin Forum © 2020 Originlab Corporation Go To Top Of Page
Snitz Forums 2000