# Question regarding coordinates received by uboun.f subroutine

**URL:** <https://calculix.discourse.group/t/question-regarding-coordinates-received-by-uboun-f-subroutine/977>\
**Category:** Uncategorized\
**Created:** [January 29, 2022, 11:03pm UTC](https://calculix.discourse.group/t/question-regarding-coordinates-received-by-uboun-f-subroutine/977 "2022-01-29T23:03:16Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Andres](https://avatars.discourse-cdn.com/v4/letter/a/a4c791/32.png) [@Andres](https://calculix.discourse.group/u/Andres)\
**Post date:** [January 29, 2022, 11:03pm UTC](https://calculix.discourse.group/t/question-regarding-coordinates-received-by-uboun-f-subroutine/977/1 "2022-01-29T23:03:16Z")

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Hey everyone,

I have a simple question regarding the subroutine for user-defined boundary values (`uboun.f`). That subroutine receives the coordinates of the node(s) on which the boundary condition(s) is (are) applied. Are those the node’s coordinates in the reference configuration or the node’s coordinates in the spatial configuration?

I’d appreciate it if someone could clarify this.

Regards,  
Andrés

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**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\
**Post date:** [January 29, 2022, 11:45pm UTC](https://calculix.discourse.group/t/question-regarding-coordinates-received-by-uboun-f-subroutine/977/2 "2022-01-29T23:45:07Z")

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This subroutine uses the `coords` variable which should contain the current coordinates of the nodes - if geometric nonlinearity is enabled, they will be updated, otherwise, they will keep their original values.

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**Author:** ![Andres](https://avatars.discourse-cdn.com/v4/letter/a/a4c791/32.png) [@Andres](https://calculix.discourse.group/u/Andres)\
**Post date:** [January 30, 2022, 1:43pm UTC](https://calculix.discourse.group/t/question-regarding-coordinates-received-by-uboun-f-subroutine/977/3 "2022-01-30T13:43:50Z")

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That was exactly what I wanted to know. Thanks!

Related questions:

- In a case with geometric nonlinearities, would it be possible the provide `uboun.f` with the node’s original values?
- This one is slightly off-topic but in a way related to the previous ones: when specifying a local cylindrical coordinate system with `*TRANSFORM`, imposed displacements in the 2nd degree of freedom (tangential) must be expressed in radians, correct?

Andrés

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<div class="post-metadata">

**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\
**Post date:** [January 30, 2022, 2:54pm UTC](https://calculix.discourse.group/t/question-regarding-coordinates-received-by-uboun-f-subroutine/977/4 "2022-01-30T14:54:28Z")

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> [@Andres](#):
>
> In a case with geometric nonlinearities, would it be possible the provide `uboun.f` with the node’s original values?

This would likely require quite significant modification of the source code.

> [@Andres](#):
>
> This one is slightly off-topic but in a way related to the previous ones: when specifying a local cylindrical coordinate system with `*TRANSFORM` , imposed displacements in the 2nd degree of freedom (tangential) must be expressed in radians, correct?

Yes, the unit will be radian in such a case.

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<div class="post-metadata">

**Author:** ![Andres](https://avatars.discourse-cdn.com/v4/letter/a/a4c791/32.png) [@Andres](https://calculix.discourse.group/u/Andres)\
**Post date:** [January 30, 2022, 5:43pm UTC](https://calculix.discourse.group/t/question-regarding-coordinates-received-by-uboun-f-subroutine/977/5 "2022-01-30T17:43:11Z")

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Understood. Thanks again!

Andrés