## 3.1. Windows Systems using MPI

Autodyn is made available on Windows operating systems using MPI as the parallel message passing protocol. Dynamic spawning of slave processes from the Autodyn component system is not possible. Therefore the number of slave tasks is specified before starting the Autodyn program using `mpirun` or `mpiexec` depending on the MPI provider used. The process for this is outlined in the following sections. Once the Autodyn executable is started the user would have to restart their Autodyn session should they require a different number of slave tasks.

Note: The recommended method of running an Autodyn job using MPI is by using the AUTODYNWRAPPER.exe file, which is described in Running Autodyn on Windows Platforms. The alternative methods of starting an Autodyn parallel job give you the ability to add other MPI options that are not supported by AUTODYNWRAPPER.exe, but should only be used if those MPI options are needed.

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