A comparison of two Fortran dialects for expressing parallel solutions for a problem in linear algebra

Abstract

Recently, AMT has issued an extended version of Fortran Plus [1] which allows software to be developed without the developer needing to take explicit accout of the grid size of the target processor. Fortran-Plus and its extension, Fortran Plus Enhanced [2], have been developed for use on the AMT DAP 510 array processor. This machine has 1024 processors arranged in a square grid with nearest neighbour and wraparound connections. It is interesting to enquire whether the performance of code generated by the Fortran-Plus Enhanced compiler is, for a particular application, superior to that generated by the Fortran-Plus compiler from a program which recognises and is tailored to fit the characteristic features of the DAP 510. In this paper the performances of two implementations of an algorithm for the eigensolution of real tridiagonal symmetric matrices are compared. The algorithm is characterised by its heavy use of matrix operations, all of which can be efficiently implemented on an array processor. Some of the constituent operations commonly occur in other applications while others are specific to the problem being addressed.