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Viewing the whole equation system

Posted Jan 4, 2012, 9:00 a.m. EST Results & Visualization, Studies & Solvers Version 4.1, Version 4.3a 5 Replies

Norbert Bartscher
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Hello,

is it somehow possible to take a look at the whole equation system, COMSOL has built, after it was solved?

Thanks is advance.
5 Replies Last Post Apr 9, 2014, 5:03 a.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Jan 4, 2012, 9:57 a.m. EST
Hi

what do you exactly mean by the "hole equation system" ?, You get many details in the "complete report", you can see the individual equations in the equation view, and you can extract the main matrices (quite a job as these are mostly huge and sparse) at least with matlab or via API I believe

--
Good luck
Ivar
Hi what do you exactly mean by the "hole equation system" ?, You get many details in the "complete report", you can see the individual equations in the equation view, and you can extract the main matrices (quite a job as these are mostly huge and sparse) at least with matlab or via API I believe -- Good luck Ivar
Bahar
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Posted: 1 decade ago Jan 4, 2012, 4:44 p.m. EST
As Ivar said, you can view the equations which are being used in your system setting. I have 4.2 and in this version you can active this, from top of your model builder section. Just put check marks besides the option about equation.

Good Luck
Bahareh

As Ivar said, you can view the equations which are being used in your system setting. I have 4.2 and in this version you can active this, from top of your model builder section. Just put check marks besides the option about equation. Good Luck Bahareh
Norbert Bartscher
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Posted: 1 decade ago Jan 9, 2012, 7:27 a.m. EST
Hello,

thanks for your answers.
What I am looking for is the complete matrix vector multiplication of a model.

For example: Electrostatics, linear triangle approach:
Capacitor with 2 boundary conditions (high and low potential) and a mesh built out of 4 triangles -> 6 knots.
This should result in 6 Potential equations.


I am looking exactly for these equations, after COMSOL had put numbers in it.
I am NOT looking for the general equations you can find in the model builder., like:

E=-grad Phi

Thanks in advance
Hello, thanks for your answers. What I am looking for is the complete matrix vector multiplication of a model. For example: Electrostatics, linear triangle approach: Capacitor with 2 boundary conditions (high and low potential) and a mesh built out of 4 triangles -> 6 knots. This should result in 6 Potential equations. I am looking exactly for these equations, after COMSOL had put numbers in it. I am NOT looking for the general equations you can find in the model builder., like: E=-grad Phi Thanks in advance
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Jan 9, 2012, 7:45 a.m. EST
Hi

then I would say study the Matlab livelink and get the data from there

--
Good luck
Ivar
Hi then I would say study the Matlab livelink and get the data from there -- Good luck Ivar
Shoshana Spellman
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Posted: 1 decade ago Apr 9, 2014, 5:03 a.m. EDT
Hi,

Saw this post from a year ago and was wondering the same thing - I've been trying to find a way to see exactly what COMSOL is doing in order to produce the results I see. Were you able to find a way to see this? I see that one recommendation was to use the MATLAB livelink, I am a fairly new user and have not yet used the livelink but have been meaning to figure out how - did this help you to see the equations, and if so can you please let me know what it required? I am familiar with MATLAB but have never used it together with COMSOL.

Thanks!
Shoshana
Hi, Saw this post from a year ago and was wondering the same thing - I've been trying to find a way to see exactly what COMSOL is doing in order to produce the results I see. Were you able to find a way to see this? I see that one recommendation was to use the MATLAB livelink, I am a fairly new user and have not yet used the livelink but have been meaning to figure out how - did this help you to see the equations, and if so can you please let me know what it required? I am familiar with MATLAB but have never used it together with COMSOL. Thanks! Shoshana

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