HI. Say,I have 10 process，each one has a array called gbest, I want to get the min array(with a compare operation I want to define). Is there a way to use MPI_REDUCE to do this?As I know, MPI_MIN specifies datatypes(without arrays). ------------------ Jie-Jun Wu Department of Computer Science, Sun Yat-sen University, Guangzhou, P.R. China