# Error in MPC while using \*EQUATION

**URL:** <https://calculix.discourse.group/t/error-in-mpc-while-using-equation/612>\
**Category:** Uncategorized\
**Created:** [June 10, 2021, 10:58pm UTC](https://calculix.discourse.group/t/error-in-mpc-while-using-equation/612 "2021-06-10T22:58:09Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![bhanups1991](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/bhanups1991/32/287_2.png) [@bhanups1991](https://calculix.discourse.group/u/bhanups1991)\
**Post date:** [June 10, 2021, 10:58pm UTC](https://calculix.discourse.group/t/error-in-mpc-while-using-equation/612/1 "2021-06-10T22:58:09Z")

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Hi

I want to apply a periodic boundary condition using the MPC constraint.  
I think \*EQUATION is the right card for it. Is it not?

ABAQUS allows to use a node-set with \*EQUATION, but I guess in CalculiX we can’t apply the MPC on a node-set directly ! Any comments?

Thanks

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**Author:** ![jbr](https://avatars.discourse-cdn.com/v4/letter/j/ecccb3/32.png) [@jbr](https://calculix.discourse.group/u/jbr)\
**Post date:** [June 11, 2021, 4:38am UTC](https://calculix.discourse.group/t/error-in-mpc-while-using-equation/612/2 "2021-06-11T04:38:54Z")

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Hi @bhanups1991, I think you are right. Please take a look at Dr. Kraska’s scripts and see if this works for you:  
[Dr. Kraska Parametric CalculiX-Examples](https://github.com/calculix/mkraska/tree/master/RVE/Periodic).

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**Author:** ![bhanups1991](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/bhanups1991/32/287_2.png) [@bhanups1991](https://calculix.discourse.group/u/bhanups1991)\
**Post date:** [June 11, 2021, 7:53am UTC](https://calculix.discourse.group/t/error-in-mpc-while-using-equation/612/3 "2021-06-11T07:53:41Z")

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Thanks @jbr , I’ll check.  
Let me get back here if the problem still remains.