# How can I ofstream the values of macros in my code?

**URL:** <https://community.freefem.org/t/how-can-i-ofstream-the-values-of-macros-in-my-code/2076>\
**Category:** General Discussion\
**Created:** [October 21, 2022, 12:11pm UTC](https://community.freefem.org/t/how-can-i-ofstream-the-values-of-macros-in-my-code/2076 "2022-10-21T12:11:22Z")\
**Posts on this page:** 1\
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**Author:** ![aszaboa](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/aszaboa/32/2918_2.png) [@aszaboa](https://community.freefem.org/u/aszaboa)\
**Post date:** [October 21, 2022, 1:33pm UTC](https://community.freefem.org/t/how-can-i-ofstream-the-values-of-macros-in-my-code/2076/3 "2022-10-21T13:33:27Z")

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Essentially, you want to export the valued of a scalar/vectorial FE space on the boundaries. I think you could use the same method as the one discussed in [this](https://community.freefem.org/t/exporting-boundary-value/2028) post. To calculate the traction vector, you can just specify a FE field with the normal vectors - something similar is explained [here](https://community.freefem.org/t/normal-boundary-condition/341/6).

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