Discussion Forum

I am using the Parameter Estimation to try fit my model to experimental data. Specifically, I am trying to fit a diffusion coefficient to cumulative release data. I find cumulative release in the model by integrating over the domain where the has species diffused into. Thus, I've set up an integral operator under the component tree to do so.

When I use the integration operator in the model expression field and run the parameter estimation, comsol throws the error "Unknown function or operator" and lists the integral operator as the source.

My current guess is that its because the integration operator isn't defined globally so it doesn't know it exists. I've tried adding comp1 infront of it (the form comp1.intop(conc)) but it still had the same issue. Is this a global/local issue that there's a way to fix, or is there something else I'm missing?