Greetings,
We have a user-subroutine that gets compiled and linked as a DLL to Finite Element Solver, Abaqus. Part of our subroutine is a matrix inversion subroutine that is inverting a 6x6 symmetric matrix. The subroutine we use is the one form https://people.sc.fsu.edu/~jburkardt/f_src/asa007/asa007.f90
The problem is that when the Abaqus simulation is run using a single cpu, the analysis runs fine. But when we use multiple cpus, it reports NANs.
Please note that the stiffness matrix being inverted can have a condition number of up to 1E7.
I wonder what can be the root cause of such problem. Can it be related to the matrix condition number?
Thanks,
Alireza