I am trying to solve a set of PDEs using a combination of MATLAB (to run the loop) and COMSOL. Then I use the output of COMSOL and after small process the output of COMSOL which is loaded in MATLAB should be imported again into COMSOL model to update first variables. It is easy to import data from COMSOL to MATLAB but it is difficult to do the reverse. I am looking for straight way to import data from MATLAB to COMSOL. I should mention it is possible to write the data in txt file and then import it by interpolation but I don’t need interpolation on the data and this seems to increase the total running time drastically. Does anybody have any suggestions?
Thank you
There are several ways of combining Comsol with external software. In my experience, the best way of communication is through the Java interface. Calling Comsol from Matlab is also easy. It's possible to call Matlab functions from withing Comsol as well, but this is a hazzle..
In my experience, using txt files and import by interpolation is the best way to go. But it depends on your problem. It would help with a more detailed explanation. What kind of data are you trying to import?
Hi, thank you for your answer.
I am doing kind of self-consistent solution and I take out the Eigenvectors "u"(the output of a 1D eigenvalue PDE). After some process at the end of first iteration, I have an array of real digits, just like a matrix with one column. Each of this digits represent a dependent variable (which are function of position). As you know, it is possible to reset a constant values through MATLAB (with kind of command "Set Parameters"). Such kind of constants were already defined in COMSOL. I need such thing but for a variable. Moreover, I strongly believe writing data in txt file (by MATLAB) and reading it (by COMSOL) will decrease the speed drastically. Since numerical solution is all about replacing new data with the old one, there should be some way to replace new variable but in this case I like to do this by some MATLAB command.
It may perhaps sound like a big deal to read and write data to a txt file, but in my experience, this is a fast process, especially if you use Matlab's built-in functions for writing txt files. So, in short, I don't believe you when you say that the speed is drastically decreased by this. Usually the read/write time is only a fraction of the Comsol solution time, but it depends to some degree on how many iterations you require.
If the Matlab function you are trying to call is simple, it may be worth re-writing the code in Java, since it's much easier to call a Java function from Comsol. But it may also be that you are going to use more time on re-writing the code, than what you save during the solution process.
A third alternative is to call Matlab from Comsol. But I won't recommend it. Comsol has to startup another instance of Matlab to get access to the function, and this is much more time-consuming than reading a txt file.
Yet another alternative is to create a "file" that actually resides in memory. Such files are extremely fast to create and read. The way of creating one is dependent on your operating system, a google search on "RAM disk" should give you some hints. But as I have stated previously, I don't believe that you actually need this.
Thank you very much for your advance reply. So, I will continuing using txt files, till I understand who to connect those software in a better ways.
- Badges
- Science topic