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error code 7161

Posted Mar 31, 2010, 10:27 a.m. EDT 2 Replies

Sicheng Zhou
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Hej, everyone

I am making a simulation with Optimization Lab.
And I get an error which has the code 7161 with a message "The mass matrix is zero".

Can any one tell me what does this mean?

Thanks.
Regards.
2 Replies Last Post Jul 12, 2010, 7:38 p.m. EDT
COMSOL Moderator

Hello Sicheng Zhou

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If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.

Charles Reinke
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Posted: 1 decade ago May 26, 2010, 11:36 a.m. EDT
I had a similar problem recently using the RF module with COMSOL 3.5a on a Linux machine where I got the "error 7161: Mass matrix is zero" message. I searched the comsol.com "Knowledge Base" for an explanation, and was referred to the Multiphysics Reference Manual. Unfortunately, there is absolutely no mention of error 7161 in the COMSOL 3.5a Multiphysics Reference Manual.

What I finally figured out was that under the subdomain settings, the numerical values for the electrical conductivity (for materials I had loaded from COMSOL's materials library) contained non-numerical characters indicating the units, e.g., "1E-6[S/m]". Basically, after removing those characters, i.e. just making them all "0" (since I really didn't care about the electrical conductivity for my application), the simulation ran fine. However, it was not actually that simple, since I had to de-select the materials loaded from the library and then enter the values by had for the various materials, and even after removing the "[S/m]" characters, I would get an "error 7111: SIngular matrix" for any non-zero values, so this still could be a problem if I ever need a nonzero electrical conductivity. I'm not sure if this is just a materials library issue with the Linux version of COMSOL 3.5a, or if the bug is more pervasive than that.

The way this was discovered was from the stack trace of the error message. When the error message pops up, there is a little button on the dialog box called "Details >>". If you hit that, it shows you some information about what is going wrong, including a section called "Stack trace". In my case, several of the lines in that section mentioned "Unknown Source", and when I went into subdomain settings for "Physics", that is where I saw the extraneous characters. The bottom line is: check your subdomain settings for any non-numerical characters in the values, particularly for properties loaded from the materials library.

Hope that this helps someone.
I had a similar problem recently using the RF module with COMSOL 3.5a on a Linux machine where I got the "error 7161: Mass matrix is zero" message. I searched the comsol.com "Knowledge Base" for an explanation, and was referred to the Multiphysics Reference Manual. Unfortunately, there is absolutely no mention of error 7161 in the COMSOL 3.5a Multiphysics Reference Manual. What I finally figured out was that under the subdomain settings, the numerical values for the electrical conductivity (for materials I had loaded from COMSOL's materials library) contained non-numerical characters indicating the units, e.g., "1E-6[S/m]". Basically, after removing those characters, i.e. just making them all "0" (since I really didn't care about the electrical conductivity for my application), the simulation ran fine. However, it was not actually that simple, since I had to de-select the materials loaded from the library and then enter the values by had for the various materials, and even after removing the "[S/m]" characters, I would get an "error 7111: SIngular matrix" for any non-zero values, so this still could be a problem if I ever need a nonzero electrical conductivity. I'm not sure if this is just a materials library issue with the Linux version of COMSOL 3.5a, or if the bug is more pervasive than that. The way this was discovered was from the stack trace of the error message. When the error message pops up, there is a little button on the dialog box called "Details >>". If you hit that, it shows you some information about what is going wrong, including a section called "Stack trace". In my case, several of the lines in that section mentioned "Unknown Source", and when I went into subdomain settings for "Physics", that is where I saw the extraneous characters. The bottom line is: check your subdomain settings for any non-numerical characters in the values, particularly for properties loaded from the materials library. Hope that this helps someone.
Matthew Puckett
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Posted: 1 decade ago Jul 12, 2010, 7:38 p.m. EDT
Helped me a lot, had the exact same problem just now. Thanks!
Helped me a lot, had the exact same problem just now. Thanks!

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