Hi, I noticed that MPICH's MPI_Dims_create() fails with a floating point exception, if the number of processes is larger than 10^6. Apparently the reason is that the prime factors are hard coded into the code and are limited to 1000 (or sqrt(10^6)). Open MPI's implementation has no such limitation. Best -Andreas -- ========================================================== Andreas Schäfer HPC and Grid Computing Chair of Computer Science 3 Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany +49 9131 85-27910 PGP/GPG key via keyserver http://www.libgeodecomp.org ========================================================== (\___/) (+'.'+) (")_(") This is Bunny. Copy and paste Bunny into your signature to help him gain world domination!