IMSL Libraries Implementation on BULL GCOS8 Supermainframes: Getting an Optimized BLAS Level 1

In this paper we describe the work done to get a standard version of FORTRAN IMSL Libraries tailored for vector supermainframes, checking for and removing pathologic situations which inhibit vectorization. Attention is then paid to analyse how to improve library performance in the DPS 9xxx GCOS8 vector environment. For this aim, the modular structured approach of BLAS Level 1 package has been followed, implementing a specific optimized version for the GCOS8 FORTRANN 77/ESV compiler, starting from the IMSL proposed set. Then DPS 9000 performance results are showed, both on IMSL original and BULL modified BLAS1 subprograms. As examples, subroutine SAXPY and function ISAMAX are chosen while explaining modifications and related improvements. Some considerations about implementation benefits, package portability and possible follow on of the realized work, with particular regard for complex data routines, conclude the article.