# Questions tagged [petsc]

PETSc is an open source suite of data structures and routines for the scalable (parallel) solution of scientific applications modeled by partial differential equations.

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### Is it possible to predict the null space of a structure from contributing elements null spaces?

I am trying to solve an almost incompressible problem with heterogeneous properties by domain decomposition. Solution with CG converges slowly or divergerces completely. My problem becomes ill-...
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### Solving saddle point problem having non-invertible top-left block with a PETSc nested matrix

My system is a symmetric FE problem with lagrange multipliers: $Z=\begin{pmatrix}A & C^T \\ C & 0\end{pmatrix}$ The matrix $A$ is positive semi-definite, non-invertible. The whole matrix is ...
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### PETSc SNES for user defined state

How to use PETSc SNES (scalable nonlinear equation solver), when the solution is not a vector but a user defined state? I am implementing a non-linear mechanics problem (geometrically exact shell 5-...
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### Method with low memory requirement for large-scale eigenvalue problem

I am working on the flow stability problem. In this work the main complication is solving generalized eigenvalue problem for a large scale Non-Hermitian matrix. I need only one eigenvalue (most left ...
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### Is there an easy way to read a PetscBag into a python dict?

I'm using a PetscBag to store the input parameters of my program. At some point, I'm going to need to use python to plot these parameters against some output parameters, and ...
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### Parallel dense solve with submatrices from mesh refinement with Petsc

For a Bounday Element Method problem I require the solution of a system of linear equations with multiple right-hand sides. Though this is a dense system, I still want to do it via Petsc in parallel. ...
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### PETSc - difference between PetscNew and PetscMalloc

I wonder what is the difference between both functions. In C++, the difference between new and malloc is easier: new allocates memory by calling the constructor. What about PETSc ? In the example, ...