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Matlab functions/solving transcendental equations
Posted Jan 21, 2016, 5:40 p.m. EST LiveLink for MATLAB Version 4.4 1 Reply
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Hi
I am looking to know if I can implement in comsol functions in Matlab that are dependent on two input variables --- spatial location as well as species concentration. I have a Matlab function to solve a transcendental equation which then gives me the reaction rate term in my species transport model in comsol. My matlab function works just fine but then I am not sure how I can call this function from within comsol. My simulation is transient and therefore I am also concerned if the solver were to call comsol functions at every time step that it would slow down my model considerably.
Any other useful recommendations to solve transcendental equations? Haven't had much luck with the domain based DAEs.
Any help would be appreciated.
Thanks,
Rohini
I am looking to know if I can implement in comsol functions in Matlab that are dependent on two input variables --- spatial location as well as species concentration. I have a Matlab function to solve a transcendental equation which then gives me the reaction rate term in my species transport model in comsol. My matlab function works just fine but then I am not sure how I can call this function from within comsol. My simulation is transient and therefore I am also concerned if the solver were to call comsol functions at every time step that it would slow down my model considerably.
Any other useful recommendations to solve transcendental equations? Haven't had much luck with the domain based DAEs.
Any help would be appreciated.
Thanks,
Rohini
1 Reply Last Post Jan 22, 2016, 4:23 p.m. EST
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Posted:
9 years ago
Hello Rohini,
Domain-based DAE's would be an appropriate way to solve transcendental equations, and more efficient than additionally calling MATLAB. In the DAE's interface ou could enter a source term, f, of for example: sin(u)-exp(-u) and leave all other terms at zero. This will solve for u such that sin(u)=exp(-u).
There is an example given, and a discussion about the importance of initial conditions, in this video:
www.comsol.com/video/equation-based-modeling-custom-simulations-comsol-multiphysics
Domain-based DAE's would be an appropriate way to solve transcendental equations, and more efficient than additionally calling MATLAB. In the DAE's interface ou could enter a source term, f, of for example: sin(u)-exp(-u) and leave all other terms at zero. This will solve for u such that sin(u)=exp(-u).
There is an example given, and a discussion about the importance of initial conditions, in this video:
www.comsol.com/video/equation-based-modeling-custom-simulations-comsol-multiphysics