Zero pivot error when using pylith 4.1.3

PyLith
1

Hello all,

I built 3D model to simulate interseimic deformatin following the step03 in example/subduction-3D. once I precribe slip rate on the fault, the zero pivot apears. Attachments are configure files and error log file.
Many thanks!
error.zip (1.3 MB)

2

We strongly recommend that you update to PyLith v4.2.0. It fixes a bug related to determining a consistent orientation of the fault surface.

A zero pivot means that the Jacobian matrix for the system of equations has a null space. A common way for this to happen is when there are insufficient Dirichlet boundary conditions to prevent rigid body motion (translation or rotation of the entire domain) or you have multiple faults crossing the entire domain without boundary conditions that constrain rigid body motion of the portion between the two faults.

If you cannot resolve the issue based on the above guidance, then provide a diagram or sketch of the boundary value problem you are trying to solve. For more detail about requesting help, please refer to

3

Dear baagaard,

Thank you so much for your response.

I encountered dependency issues (glibc) while trying to install PyLith 4.2 on the server. I opted to install PyLith 4.2 in the virtual machine of my laptop instead. but the zero pivot still ocurrs.

  1. Pylith 4.2 building from source in the virual machine of ubuntu-24.04.2-desktop-amd64.
  2. Describe what you are trying to do
  • Overview of the boundary value problem (diagrams are very helpful)
    I am working on solving an interseismic deformation problem where the boundary conditions are constrained by GNSS velocities. The faults cross the upper crust and separate different blocks. Currently, I have only prescribed a uniform slip on one of the faults. (diagram is in the attachment)
  • Software used to generate the mesh: Cubit 2024.8
  • Cell type: tet
  • Type of fault: prescribed slip
  1. Attach the PyLith parameters .json file and entire error message are in the attachment
    information.zip (125.4 KB)

Looking forward to your response.
Many thanks