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Subsection 8.10.4: Force-driven Problems Up Section 8.10: Limitations of FEBio Section 8.11: Where to Get More Help

### 8.10.5 Solutions obtained on Multi-processor Machines

Although technically not a limitation of FEBio it is important that users are aware that in some cases you may get a different convergence history or sometimes even a slightly different answer when you run the same model twice on a multi-processor machine. This is caused by the fact that on multi-processor machines the same calculations can be executed in a different order and due to the accumulation of numerical round-off errors may result in slightly different answers. The type of problems that are mostly affected by this are problems that are close too being ill-conditioned. Also, problems that have many time steps or require many iterations for each time step may be affected by this.
If you experience different answers for the same problem, try running the model on just one processor (if possible). See Section 2.6↑ for more information on how to run FEBio on multi-processor machines.
Subsection 8.10.4: Force-driven Problems Up Section 8.10: Limitations of FEBio Section 8.11: Where to Get More Help