Implementation of a Parallel Output for the Phylogenetic
                     Tree Programm MrBayes

                       Amir Rais Zeervi


                            Abstract

Many scientific applications need parallel I/O. MrBayes 3.1 is a
program for the Bayesian estimation of phylogeny. Like many other
applications, it is implemented with Message Passing Interface (MPI)
and uses the concept of sequential I/O to write data into several
output files. In the current version of MrBayes 3.1 the processes send
their data to a master process which writes the received data into the
files. The main issue of this work is to change the non-parallel
output of MrBayes 3.1 with MPI-IO Interface to parallel I/O, so that
the sampled parameters of an analysis could be written to a single
file. In order to increase performance different file mappings are
possible. The most suitable mapping for the output data is proposed in
this work. It is shown how to partition a single file with different
file views and how derived data types can be used to write complex
data structures.