Discussion Forum

Hi

usually you find these kind of info in the command.pdf and mlinterface.pdf, check the "postglobaleval", and run an indexed search on your doc files as the examples are scattered around in the different documents

Good luck
Ivar

Thank you very much, Ivar. I just was focused on COMSOL options and I did not realize that MATLAB commands could be used.

plot the global variable you want to export and in the plot wind0w you have an " ascii" button that save the plotted variable in a text file.
jf

Hi

pls note ther is a little bug in the ascii dump for long files with multiple plots, the columns get slightly mixed up, check carefully the results, it does not alsway show up, depends on plot data length

This has been discussed a couple of times before, pls try a search on the forum

Good luck
Ivar

Thank you all, the ascii button fits with my purposes.
Lidia.

Hi Ivar,

In COMSOL 3.5 one was allowed to specify co-ordinates @ which data should be exported from. This was enabled by the "Get co-ordinates from, 'textfile' " option. Comsol 4a does not seem to allow one to do this. Any idea why they have removed this function? What is the work around?

Thanks

Tiaan

and what is the equivalent in Comsol 4? Say I want to export temperature along a boundary, or more complex: a surface data to matlab.


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Comsol 4.0a
Ubuntu 10.04.1

HI

I can only say what I do: send in suggestions to "suggest at comsol" that are sufficiently documented that thy see the advantages, then your suggestions have, if generic enough, a great chance to appear on next version

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Good luck
Ivar

Regarding the questions posted earlier in this thread:

(1) "In COMSOL 3.5 one was allowed to specify co-ordinates @ which data should be exported from. This was enabled by the "Get co-ordinates from, 'textfile' " option. Comsol 4a does not seem to allow one to do this. Any idea why they have removed this function? What is the work around?"

By defining a Cut Point data set and choose that in the export you can specify for which coordinates the data should be evaluated. In the upcoming version 4.1 the cut point coordinates can be a grid of coordinates values and not just a single point.

(2) "and what is the equivalent in Comsol 4? Say I want to export temperature along a boundary, or more complex: a surface data to matlab."

To get a boundary (surface) in 3D: Select "Surface" from the "Space dimension" list in the Data node's Settings window and add a selection to the Solution data set (right-click and choose "Add Selection) that is the surfaces that you want to export data from. In version 4.1 you can also use the new Edge and Surface data sets to define boundaries or surfaces for which you want to export data.

Hope this helps.

Magnus Ringh, COMSOL

I too am facing the issue of needing to export data from COMSOL 4.0 to a coordinate set defined by me. How would one create a cut point set in version 4.0? I only see a way to define the points individually. Is there a less labor intensive way to do this? I have over 75,000 points that I need to evaluate, and having to define each individual point just isn't practical. Any advice would be greatly appreciated.

Rebecca

Hi

My way would be, take it or not, to use matlab for so many "points".

But perhaps the points are aliogned on a boundary ? then you could use some projection coupling variables or a boundary "cut" (right click on data sets in v4)

One should always try (when possible) to use "higher order" entities as then one is handling the details as global items

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Good luck
Ivar