# Matrix-vector multiplication in weak formulation

**URL:** <https://community.freefem.org/t/matrix-vector-multiplication-in-weak-formulation/449>\
**Category:** General Discussion\
**Created:** [May 31, 2020, 3:14pm UTC](https://community.freefem.org/t/matrix-vector-multiplication-in-weak-formulation/449 "2020-05-31T15:14:04Z")\
**Posts on this page:** 1\
**Showing post:** 26

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**Author:** ![Lee](https://avatars.discourse-cdn.com/v4/letter/l/bc8723/32.png) [@Lee](https://community.freefem.org/u/Lee)\
**Post date:** [July 28, 2020, 3:37pm UTC](https://community.freefem.org/t/matrix-vector-multiplication-in-weak-formulation/449/26 "2020-07-28T15:37:59Z")

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Is the way of adding boundary condition in SNESSolve the same with TAO? If the initial value of boundary nodes are set to meet the requirements of boundary condition, can it be maintained using the constrain of upper and lower bound or using the form as on(1,2,3,4, du1=0,du2=0,du3=0) in varf function?

Thank you for your reply.

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