# Problem with UMPACK - VirtualSolverCG.hpp

**URL:** <https://community.freefem.org/t/problem-with-umpack-virtualsolvercg-hpp/2589>\
**Category:** General Discussion\
**Created:** [July 9, 2023, 5:34am UTC](https://community.freefem.org/t/problem-with-umpack-virtualsolvercg-hpp/2589 "2023-07-09T05:34:42Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![Loic](https://avatars.discourse-cdn.com/v4/letter/l/e9c0ed/32.png) [@Loic](https://community.freefem.org/u/Loic)\
**Post date:** [July 9, 2023, 5:34am UTC](https://community.freefem.org/t/problem-with-umpack-virtualsolvercg-hpp/2589/1 "2023-07-09T05:34:42Z")

</div>

Dear all,

I have a Stiffness matrix and an RHS Matrix, that I solve with :

```auto
set(StiffGlobal, solver=UMFPACK);
xx=StiffGlobal^-1*RHSGlobal;

```

When I do this in local on my machine, there is no problem. However when I do the same thing on a cluster, I get this error :

```auto
Error: fgmres do not converge nb end =1
  current line = 19
Assertion fail : (0)
        line :254, in file ../femlib/VirtualSolverCG.hpp
Assertion fail : (0)
        line :254, in file ../femlib/VirtualSolverCG.hpp
 err code 6 , mpirank 0

```

Is there another argument to add in the solver ?

Here my code to reproduce this example.  
[Test\_UMFPACK.zip](https://community.freefem.org/uploads/short-url/1rsxY1Hpty9a8YHkpctUaKEJxbW.zip) (16.4 KB)

Thank you in advance,

Best regards,

Loïc,

---

<div class="post-metadata">

**Author:** ![prj](https://avatars.discourse-cdn.com/v4/letter/p/ecae2f/32.png) [@prj](https://community.freefem.org/u/prj)\
**Post date:** [July 9, 2023, 6:13am UTC](https://community.freefem.org/t/problem-with-umpack-virtualsolvercg-hpp/2589/2 "2023-07-09T06:13:48Z")

</div>

You probably don’t have SuiteSparse installed on your machine, so it switches to another solver by default.

---

<div class="post-metadata">

**Author:** ![prj](https://avatars.discourse-cdn.com/v4/letter/p/ecae2f/32.png) [@prj](https://community.freefem.org/u/prj)\
**Post date:** [July 9, 2023, 6:19am UTC](https://community.freefem.org/t/problem-with-umpack-virtualsolvercg-hpp/2589/3 "2023-07-09T06:19:40Z")

</div>

```auto
// set(StiffGlobal, solver=UMFPACK);
// xx=StiffGlobal^-1*RHSGlobal;
load "PETSc"
Mat StiffGlobalPETSc(StiffGlobal);
set(StiffGlobalPETSc, sparams = "-pc_type lu -pc_factor_mat_solver_type mumps");
xx=StiffGlobalPETSc^-1*RHSGlobal;

```

This will get the code to run even without SuiteSparse.

---

<div class="post-metadata">

**Author:** ![Loic](https://avatars.discourse-cdn.com/v4/letter/l/e9c0ed/32.png) [@Loic](https://community.freefem.org/u/Loic)\
**Post date:** [July 9, 2023, 6:31am UTC](https://community.freefem.org/t/problem-with-umpack-virtualsolvercg-hpp/2589/4 "2023-07-09T06:31:12Z")

</div>

Thanks !

It works,

Best regards,

Loïc,