Integrating library modules into special purpose parallel algorithms

Most programs from scientific computing can benefit from the use of numerical libraries which provide efficient implementations for standard solution methods that often occur in numerical simulations. This is especially true for parallel scientific computing. A methodology that allows the integration of library functions without any additional programming effort would ease this programming style. In this paper, we address the question how to integrate library procedures into hierarchically organized parallel programs. The hierarchical structure of a specific algorithms results from a top-down decomposition into submethods which can be realized by library functions. The integration of library functions not only requires a correct specification of data dependencies between different modules but has also to take into account a possible distribution of data among the processors. We present algorithms for the adaptation of library modules such that their functional type and underlying data distribution fit into the hierarchical framework. The adaptation includes the construction of data flow graphs that can be used to determine data distributions for the library modules such that a minimal global execution time results.