Discussion Forum

Hi,

I am not exactly sure what you mean by parallel code. It is possible to set up external functions and external material models. For this you need to make a DLL in your preferred development system and COMSOL will call the DLL at each solver call, e.g. at each time step. You can run any code in such a DLL. This is for Windows, I think the Linux version has similar mechanisms. The model builder allows model methods in JAVA, but I don't think they can be called during computation. I am sometimes using them to set parameters and for post processing. Check the documentation.

Cheers, Edgar

Hi,

I am not exactly sure what you mean by parallel code. It is possible to set up external functions and external material models. For this you need to make a DLL in your preferred development system and COMSOL will call the DLL at each solver call, e.g. at each time step. You can run any code in such a DLL. This is for Windows, I think the Linux version has similar mechanisms. The model builder allows model methods in JAVA, but I don't think they can be called during computation. I am sometimes using them to set parameters and for post processing. Check the documentation.

Cheers, Edgar

HI Edgar, thanks for answer. There is way to use methods during computatin but basically I use JAVA methods for post processing.

The example I provided is legit JAVA code which works but not in Comsol. Thanks for the idea with external DLL. It's great and useful tool but it does not fit what I want to try.

For example we have parametric sweep with 3 steps, where 1, 2, 3 are indeces of those steps. In postprocessing we need to perform Global Evaluation for each step independently. I will omit imports, class name and execute method of the class method11 and show simple example:

int[] indeces = new int[]{1, 2, 3};
for (int i: indeces)
{
    with(model.result().numerical("sol2"));
        set("outersolnumindices", i);
    endwith();
    model.result().numerical("gev1").setIndex("expr", "2+" + toString(i), 0);
    model.result().numerical("gev1").setResult();
}
double[][] table = model.result().table("tbl1").getReal();

Previous code is a sequence. Next example suppose to be legit equivalent of previous.

int[] indeces = new int[]{1, 2, 3};
List<Integer> mylist = Arrays.asList(indeces);
mylist.parallelStream().map(i-> {
    with(model.result().numerical("sol2"));
        set("outersolnumindices", i);
    endwith();
    model.result().numerical("gev1").setIndex("expr", "2+" + toString(i), 0);
    model.result().numerical("gev1").setResult();
});
double[][] table = model.result().table("tbl1").getReal();
// 'i' cannot be resolved to a variable.

But this code should run for each index i an independent subprogram in the same time.

I suspect that it's impossible to do in the way I want but at least to have an option to run parallel JAVA code would be nice.

Best Regards, Kostiantyn Vasko

You can submit model parameters to an external material and receive states from it.

You can submit model parameters to an external material and receive states from it.

Do you have a simple example of what you describing?

There are examples in the documentation. Unfortunately all I have is protected by confidentiality agreements and it is not exactly simple as well.

I would also advise to contact COMSOL support. I got examples from them when I started to look into external materials, but I don't think I am allowed to share this with other users.