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how to over come error ''Single Matrix''

Posted Apr 7, 2011, 8:43 a.m. EDT RF & Microwave Engineering, Studies & Solvers Version 4.0 5 Replies

Rashedul Karim
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Hi All gentlemen,
during my solving an error notic is coming and terminating my computation. the message is show bellow


Feature: stationary1(sol1/s1)
Error: Single Matrix.

Could anyone may give some tips to avoid this error?

Regards,

Rashedul
5 Replies Last Post Nov 13, 2012, 3:09 p.m. EST
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Apr 7, 2011, 9:22 a.m. EDT
Hi

I assume it "singular matrix" which typically mean that you are missing some BC or that your PDE is not set up well enough to give a single unique response

--
Good luck
Ivar
Hi I assume it "singular matrix" which typically mean that you are missing some BC or that your PDE is not set up well enough to give a single unique response -- Good luck Ivar
Muhammad Mohsin Rehman
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Posted: 1 decade ago Apr 7, 2011, 2:45 p.m. EDT
I am also getting a similar type of error while I try to solve a controlled source electromagnetic marine model.

The title of error is :

The following feature has encounter a problem :

Feature : Stationary solver
Error : Failed to evaluate expression

Please suggest me some tricks to cope up with it.

Thanks.
I am also getting a similar type of error while I try to solve a controlled source electromagnetic marine model. The title of error is : The following feature has encounter a problem : Feature : Stationary solver Error : Failed to evaluate expression Please suggest me some tricks to cope up with it. Thanks.
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Apr 8, 2011, 1:24 a.m. EDT
Hi

then read carefully, you have somewhere an expression that cannot be resolved, a typo or a variable use out of it's context. Do not forget that variables have implicit definitions, and are often fields dependent on x,y,z, or r,t ... and mostly apply to the element of size dx,dy,dz (in 3D) therefore must sometimes be integrated over a domain or a boundary before using it in a higher order calculation

Take the density "rho" you define it as [kg/m^3] it applies to a domain, hence to the elements of the domain. Now in most formulas you use the mass of the object, not the density, so you need to integrate rho over the domain. If you have 2 domains of different materials, you need to sum over the domains the integration of the density.

This mens that "rho" is implicitly a field defined as rho_i(x,y,z,t) (as the density might change over the spatial coordinates and with time, and the _i is there to refer to the "i" individual domains. One must ALWAYS rethink carefully all formulas in COMSOL and ask the question, is this variable "global" or does it define implicitly some links to the geometry, if so is are these elements clearly defined ?

--
Good luck
Ivar
Hi then read carefully, you have somewhere an expression that cannot be resolved, a typo or a variable use out of it's context. Do not forget that variables have implicit definitions, and are often fields dependent on x,y,z, or r,t ... and mostly apply to the element of size dx,dy,dz (in 3D) therefore must sometimes be integrated over a domain or a boundary before using it in a higher order calculation Take the density "rho" you define it as [kg/m^3] it applies to a domain, hence to the elements of the domain. Now in most formulas you use the mass of the object, not the density, so you need to integrate rho over the domain. If you have 2 domains of different materials, you need to sum over the domains the integration of the density. This mens that "rho" is implicitly a field defined as rho_i(x,y,z,t) (as the density might change over the spatial coordinates and with time, and the _i is there to refer to the "i" individual domains. One must ALWAYS rethink carefully all formulas in COMSOL and ask the question, is this variable "global" or does it define implicitly some links to the geometry, if so is are these elements clearly defined ? -- Good luck Ivar
Azadeh Bagherzadeh
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Posted: 1 decade ago Nov 13, 2012, 2:31 p.m. EST
Hi
I get the same error when I am trying to solve RF module for a microwave combined with heat transfer.Also how can I apply the condition of lambart law power decay inside sample? in electromagnetic P=Pe^(-ay) please help me
Hi I get the same error when I am trying to solve RF module for a microwave combined with heat transfer.Also how can I apply the condition of lambart law power decay inside sample? in electromagnetic P=Pe^(-ay) please help me
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Nov 13, 2012, 3:09 p.m. EST
Hi
Are you sure your expression is correct I would try P*exp(-ay), but then be sure P is not already used, as for ay. I often use morecomplex names to be sure they do not mix up with COMSOL internal variables

--
Good luck
Ivar
Hi Are you sure your expression is correct I would try P*exp(-ay), but then be sure P is not already used, as for ay. I often use morecomplex names to be sure they do not mix up with COMSOL internal variables -- Good luck Ivar

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