Question about constraints

[yuesu jin]

Hi all,

  I am learning step-7 which has the same class AffineConstraints class, in step6, we use the member function ::distribute_local_to_global to put the local matrix and rhs into global matrix and rhs, but in step-7, we still use system_matrix.add and then use the constraint.condense on system_matrix and system_rhs. Do those two procedure have the same effect?

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Yuesu Jin,

Ph.D student,

University of Houston,

College of Natural Sciences and Mathematics,

Department of Earth and Atmospheric Sciences,
Houston, Texas 77204-5008


346-404-2062

[Daniel Arndt]

Yuesu,

  I am learning step-7 which has the same class AffineConstraints class, in step6, we use the member function ::distribute_local_to_global to put the local matrix and rhs into global matrix and rhs, but in step-7, we still use system_matrix.add and then use the constraint.condense on system_matrix and system_rhs. Do those two procedure have the same effect?

You can find a discussion at https://www.dealii.org/9.0.1/doxygen/deal.II/group__constraints.html. In short: Yes, they have the same purpose, but different advantages and disadvantages. In general, we recommend using distribute_local_to_global over condensation.

Best,

Daniel

[yuesu jin]

Thank you very much, Daniel!! I appreciate your help!

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