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fitting of ODE solutions to set of experimental points
Posted Nov 22, 2010, 8:10 a.m. EST 1 Reply
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-St+g*H^2-j*S=0
-Ht +b*n*exp(-t*b) - k*H - g*H^2=0
S(t0)=0
St(t0)=0
Ht(t0)=0
H(t0)=0
I need to solve two coupled ordinary differential equations shown above. Upper case letters are the coupled variables , lower case letters are parameters the ranges of which are known, t is time. St and Ht are derivatives with respect to time. Using comsol ODE tool (0th order time dependent eqautions) it is possible to solve it assuming you know the values of parameters (or their ranges) which is ok.
But...I have got experimental data which should follow the form of the variable S with only certain specific parameter values from these possible parameter ranges. I would like to import this experimental data into comsol and try to fit the solution of S in order to determine those parameters. The goal is to find these parameter values without solving equation in comsol by using a set of parameters then exporting it comparing it with experimental points in another software, then again repeating operation with other set of parameters. This can be quite time consuming and impractical . Is it possible to perform this type of 'fitting' operation operation in comsol? many thanks!
-Ht +b*n*exp(-t*b) - k*H - g*H^2=0
S(t0)=0
St(t0)=0
Ht(t0)=0
H(t0)=0
I need to solve two coupled ordinary differential equations shown above. Upper case letters are the coupled variables , lower case letters are parameters the ranges of which are known, t is time. St and Ht are derivatives with respect to time. Using comsol ODE tool (0th order time dependent eqautions) it is possible to solve it assuming you know the values of parameters (or their ranges) which is ok.
But...I have got experimental data which should follow the form of the variable S with only certain specific parameter values from these possible parameter ranges. I would like to import this experimental data into comsol and try to fit the solution of S in order to determine those parameters. The goal is to find these parameter values without solving equation in comsol by using a set of parameters then exporting it comparing it with experimental points in another software, then again repeating operation with other set of parameters. This can be quite time consuming and impractical . Is it possible to perform this type of 'fitting' operation operation in comsol? many thanks!
1 Reply Last Post Nov 22, 2010, 3:24 p.m. EST
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Posted:
1 decade ago
Hi
Comsol is only set up to solve BVP's that match it's pre-defined coefficent or global mode (which covers most if not all physics, but not all mathematics) so the trick is to re-express your ODEs into the COMSOL form, possibly by adding intermediate variables to reduce each to atmost 2nd orderd equations
--
Good luck
Ivar
Comsol is only set up to solve BVP's that match it's pre-defined coefficent or global mode (which covers most if not all physics, but not all mathematics) so the trick is to re-express your ODEs into the COMSOL form, possibly by adding intermediate variables to reduce each to atmost 2nd orderd equations
--
Good luck
Ivar