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analytik

Portugal
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Posted - 09/13/2004 :  10:32:46 AM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Origin Version (Select Help-->About Origin): Origin 6.0
Operating System: win2000

Hello everybody!

I would like to ask for help with nonlinear curve fitting where I have two Y datasets and I would like to provide simultaneously fit to two different equations.
my problem:
y_1=P1*x_1+((P2*P3*x_1)/(1+(P3*x_1)+(P4*x_1)))
y_2=P1*x_2+((P2*P4*x_2)/(1+(P3*x_2)+(P4*x_2)))
To obtain meaningful paramaters I have to apply the following constraints:
P1+P2*P3=const1;
P1+P2*P4=const2
of course the const1 & const2 are real numbers as for example: 3.1, 3.2.The Origin is responding with error message that constraints are illegal. Is there any possibility in Origin, how to solve this problem.

Thank you very much.
Analytik

Edited by - analytik on 09/22/2004 11:56:37 AM

cgbin

Albania
Posts
Posted - 09/28/2004 :  09:00:37 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
hi
this problem is easy ,you can use The Layer Tool to resolve this question.y1 is set in the first layer and y2 is set in the second layer.
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easwar

USA
1965 Posts
Posted - 09/28/2004 :  10:07:30 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi Analytik,

Currently only linear constraints are accepted by the fitter. Since your constraints are nonlinear, it is not possible to fit with them.

Easwar
OriginLab
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analytik

Portugal
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Posted - 10/07/2004 :  09:51:48 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi,

Thank you very much for your answer and I appreciate for the same. I have already found out what kind of constraints the Origin is accepting and by this way I have expressed my equations and I succeeded. Thank you very much for help.

analytik

quote:

Hi Analytik,

Currently only linear constraints are accepted by the fitter. Since your constraints are nonlinear, it is not possible to fit with them.

Easwar
OriginLab
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