How to implement constraints (conditions) to the estimation of parameters by fitting?

Hi to everyone!

How to implement in the Simbiology interface so that the estimated parameters in a fit satisfy a given condition? For example, estimate by a fit the values ​​of the kinetic constants k1 and k-1 for a serie of experimental data, which satisfy the value of the equilibrium constant Keq (Keq= k1/k-1) within a given interval, such as K= 10±2.

Thank you in advance!

Answer 1

[Jeremy Huard]

Hi @Luis B. Walter,

one idea would be to actually estimate and , with and have be calculated in the model with an initial assignment .

[Luis B. Walter]

Hi jeremy,

yes, sure.

My question was aimed at knowing if there was any way to introduce, in general, restrictions to the fitting in Simbiology. Thinking as in COPASI software, where a 'global quantity' it is defined, in our case it would be Keq=k1/k-1, and this 'global quantity' enter as a new equation (constraint) into the fitting process only assigning a value, or interval of values to Keq and the software returns the values of k1 and k-1 with their respectives standard deviation.

Thanks a lot

Luis B.

[Jeremy Huard]

Hi @Luis B. Walter,

Thanks for this input!

As of R2024a, SimBiology only supports bound constraints, both in the Model analyzer App and programmatically with sbiofit / fitProblem.

That said, if you want more general constraints, you could set up an optimization problem by writing the objective function and constraints using a SimFunction to simulate your SimBiology model and optimproblem to set up the optimization problem.

Best regards,

Jérémy

[Luis B. Walter]

Many thanks for everything, Jeremy.

best

Luis B.