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COMSOL external MATLAB function
Posted Feb 18, 2013, 9:16 a.m. EST Version 4.2 1 Reply
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Hello forum.
I want to use an external matlab function to define a local heat transfer coefficient distribution.
If I use a very simple external function, everything works fine:
for example:
function value=alpha(z)
value = ones(size(z))*65000;
end
My function will load an object with the current data from a *mat - file and will read the data and give it back to COMSOL
something like that:
function out=AlphaZ1(z)
global pipe1;
path('V:\30_Numerik\COMSOL\Thermosyphon_2.0alpha\20130218001\classes',path)
strStoredVariableDataFileName = 'V:\30_Numerik\COMSOL\Thermosyphon_2.0alpha\20130218001\pipe1.mat';
load(strStoredVariableDataFileName)
value=pipe1.CondenserSection.GetAlphaZ(z');
out=round(value');
end
Unfortunately I always get an error message:
Attempted to access value(:,1); index out of bounds because size(value)=[0,0].
with no further details
If I save the z - vector to an mat-file and later try to call the function with this z-vector, it works properly and I get the correct heat transfer distribution.
Is there a way to analyse the error message and to find where it occurs? I already tried to catch all errors with a try-catch statement in MATLAB, but that does not help
Matthias
I want to use an external matlab function to define a local heat transfer coefficient distribution.
If I use a very simple external function, everything works fine:
for example:
function value=alpha(z)
value = ones(size(z))*65000;
end
My function will load an object with the current data from a *mat - file and will read the data and give it back to COMSOL
something like that:
function out=AlphaZ1(z)
global pipe1;
path('V:\30_Numerik\COMSOL\Thermosyphon_2.0alpha\20130218001\classes',path)
strStoredVariableDataFileName = 'V:\30_Numerik\COMSOL\Thermosyphon_2.0alpha\20130218001\pipe1.mat';
load(strStoredVariableDataFileName)
value=pipe1.CondenserSection.GetAlphaZ(z');
out=round(value');
end
Unfortunately I always get an error message:
Attempted to access value(:,1); index out of bounds because size(value)=[0,0].
with no further details
If I save the z - vector to an mat-file and later try to call the function with this z-vector, it works properly and I get the correct heat transfer distribution.
Is there a way to analyse the error message and to find where it occurs? I already tried to catch all errors with a try-catch statement in MATLAB, but that does not help
Matthias
1 Reply Last Post Feb 18, 2013, 12:57 p.m. EST
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Posted:
1 decade ago
I may could specifiy the reason, but don't know any solution.
I think MATLAB has a problem during loading of object from mat-file:
(in the current folder, there is a file with the name pipe1.mat, that contains an object instance pipe1)
load pipe1;
the error message in COMSOL is (as I already have written above):
Attempted to access value(:,1); index out of bounds because size(value)=[0,0].
If I try to load the object from the MATLAB command window, everything works fine. It is possible to make it global and use it in the MATLAB external function. But the content of the object changes after each calculation step and therefore I have to load it directly within the MATLAB external function.
I think MATLAB has a problem during loading of object from mat-file:
(in the current folder, there is a file with the name pipe1.mat, that contains an object instance pipe1)
load pipe1;
the error message in COMSOL is (as I already have written above):
Attempted to access value(:,1); index out of bounds because size(value)=[0,0].
If I try to load the object from the MATLAB command window, everything works fine. It is possible to make it global and use it in the MATLAB external function. But the content of the object changes after each calculation step and therefore I have to load it directly within the MATLAB external function.