Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

What's the meaning of this error?

Please login with a confirmed email address before reporting spam

Error

Failed to evaluate variable Jacobian.
- Variable: phi
- Geometry: 1
- Domain: 1

ps: phi is the dependent variable.

Thank you!

4 Replies Last Post 2012年5月4日 GMT-4 07:30
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 2011年1月14日 GMT-5 14:54
Hi

THe jacobian is build up of the derivatives of the dependent variables, here phi, so something is not well enough defined to allow COMSOL to elaborate the derivatives of phy. Perhaps some contradiction in a BC, or a step function with two derivatives, of different values for the same (probably starting point).

--
Good luck
Ivar
Hi THe jacobian is build up of the derivatives of the dependent variables, here phi, so something is not well enough defined to allow COMSOL to elaborate the derivatives of phy. Perhaps some contradiction in a BC, or a step function with two derivatives, of different values for the same (probably starting point). -- Good luck Ivar

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 2012年5月3日 GMT-4 11:06
Hello Evar,
I am building a model of "capacitive accelerometer". And i got this error.
Moreover, i am not able to find out the dependent variable mod1.u!

Failed to evaluate variable Jacobian.
- Variable: mod1.u
- Geometry: 1
- Boundary: 1 2 3 4 9 11 112 113 114 164 204 206

Can you please help with this?

Thank you
Hello Evar, I am building a model of "capacitive accelerometer". And i got this error. Moreover, i am not able to find out the dependent variable mod1.u! Failed to evaluate variable Jacobian. - Variable: mod1.u - Geometry: 1 - Boundary: 1 2 3 4 9 11 112 113 114 164 204 206 Can you please help with this? Thank you

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 2012年5月3日 GMT-4 14:49
Hi

it's simply "u", the variable name.
The Jacobian error, most often comes from an initial value or a BC that is defined such that the derivative of u is undefined, The solver uses the estimated derivatives to choose the next solving step, but if you use bolean equations or values that become undefined in the BC definitions then COMSOL might not manage to estimate any derivatives, and then the solver fails.

--
Good luck
Ivar
Hi it's simply "u", the variable name. The Jacobian error, most often comes from an initial value or a BC that is defined such that the derivative of u is undefined, The solver uses the estimated derivatives to choose the next solving step, but if you use bolean equations or values that become undefined in the BC definitions then COMSOL might not manage to estimate any derivatives, and then the solver fails. -- Good luck Ivar

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 2012年5月4日 GMT-4 07:30
HI,
I did try changing the boundary and initial conditions. I have attached the model with this message. Can you please check the error in this and let me know how i should proceed?


Thank you

Malavika
HI, I did try changing the boundary and initial conditions. I have attached the model with this message. Can you please check the error in this and let me know how i should proceed? Thank you Malavika

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.