How to fix mumps linear solver -nan

Errors
1

Hello,

I’m trying to solve for a base-state for an arbitrary Lagrangian-Eulerian (ALE) equations problem with SNES. But I sometimes get this kind of convergence just by changing a coefficient in my equations (the Young’s modulus; for example, for some reason this doesn’t occur when I set it 100, or 150, but it does for 120, 125, 130 in my current configuration):

  0 SNES Function norm 2.566976385923e-03 
    0 KSP Residual norm 2.566976385923e-03 
    1 KSP Residual norm 2.565056301783e-13 
  1 SNES Function norm 7.325835463306e-05 
    0 KSP Residual norm 7.325835463306e-05 
    1 KSP Residual norm           -nan

with KSP convergence code -3 for an LU solve with mumps.

I asked mumps to be more verbose and the error is:

 ** ERROR RETURN ** FROM DMUMPS INFO(1)=   -1
 ** INFO(2)=               5
 ** ERROR RETURN ** FROM DMUMPS INFO(1)=   -1
 ** INFO(2)=               5
 ** ERROR RETURN ** FROM DMUMPS INFO(1)=  -20
 ** INFO(2)=        35595524
 On return from DMUMPS, INFOG(1)=             -20
 On return from DMUMPS, INFOG(2)=        35595524
    0 KSP Residual norm 3.610212198564e-05 
    1 KSP Residual norm           -nan

I followed the mumps manual for the INFOG(1)=-20 and increased the “percentage increase in the estimated working space” with

petsc4py.PETSc.Options().setValue('-mat_mumps_icntl_14', 50)

before I created my snes object. But that leads to the same error.

It should converge fine since I use the solution with Young’s modulus = 150 or 100 as the input. I also tried solving it iteratively (by creating strides and solving each individual block with LU) and it converged with no problems.

Anyone have any ideas what might cause this?

2

You may want to get in touch with mumps developers at mumps-users - MUMPS Users discussion list - subscribe