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Livelink with matlab, exporting custom expression
Posted Apr 27, 2017, 12:57 p.m. EDT 5 Replies
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I'm using livelink with Matlab to create a simulator of dielectrophoresis force. I need to export an expression like this one: d(es.normE*es.normE,x). How can i do this?
I succeed in exporting es.normE thanks to mpheval() but i got a syntax error when using the aforementioned expression.
Thanks for your helps
Vladimir
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It works for me.
What version of Comsol are you using?
What is the exact error message?
--
Lars Gregersen
Comsol Denmark
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I'm using COMSOL 5.2 (version: 220).
Here is the code:
pd=mpheval(model,'d(es.normE*es.normE,x) d(es.normE*es.normE,y)','selection','pointi');
Here is the message:
Error using mpheval (line 328)
mpheval (174): Java exception occurred:
Exception:
com.comsol.util.exceptions.FlException: Syntax error in expression
(rethrown as com.comsol.util.exceptions.FlException)
(rethrown as com.comsol.util.exceptions.FlException)
Messages:
Syntax error in expression
Syntax error in expression
Erreur de syntaxe dans une expression.
- Expression: d(es.normE*es.normE,x) d(es.normE*es.normE,y)
- Sous-expression: d(es.normE*
- Position: 2
Vladimir
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You are doing it wrong ;-)
If you wish to evaluate more than one expression you should put them in a cell array:
pd=mpheval(model, {'d(es.normE*es.normE,x)' 'd(es.normE*es.normE,y)'}, 'selection', 'pointi');
--
Lars Gregersen
Comsol Denmark
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Ok, i'm confused because this command works well:
pd=mpheval(model,'V es.normE es.Ex es.Ey','selection','pointi');
I have another question. When i evaluate with pointi defined as follow:
model.selection.create('pointi','Ball');
model.selection('pointi').set('posx','L/2');
model.selection('pointi').set('r','8');
model.selection('pointi').set('entitydim',0);
model.selection('pointi').set('condition','inside');
this select only, if any, the geometrical point inside the Ball.
If i want to create a selection on all the mesh node inside pointi, should i create firstly a geometrical domain according to pointi ?
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Ok, i'm confused because this command works well:
pd=mpheval(model,'V es.normE es.Ex es.Ey','selection','pointi');
Yes, this is a feature, but this feature only works with simple expressions and not when you are using functions with multiple parameters.
Selections work on the geometry level. Why do you need a selection of the interior mesh points?
--
Lars Gregersen
Comsol Denmark