FORTRAN VPLIB

Fortran/VPLIB Code for Matrix Matrix "Outer Product"... 

Fortran/VPLIB Code for Gauss-Jordan Matrix Inverter... 

This would certainly have resulted in an operational library in the shortest possible time but at considerable sacrifice in efficiency. All of the VPLIB subroutines were therefore written entirely in Z80A/MVP-9500 assembly language and this produced modules which contained, on average, one third of the assembler instructions produced by F80 for the same operation coded in FORTRAN. In addition to these straightforward savings a considerable amount of hand optimization was possible on the assembler level subroutines. 

Fortran Code for Matrix Multiplication using VPLIB... 

In most intstances however merely being able to arrange the calculation as a series of vector operations, without worrying over the "unit address increment" requirement, makes extremely good if not maximal use of AFPP, VP or AP. As an illustration of this point Table XIII shows "normal" FORTRAN code for a pivotal condensation matrix inverter (the author is unfortunately by now anonymous) and Table XIV shows the vectorized version for the MVP-9500 at about two thirds completion. The VPLIB version is completely (as far as the author can manage at leastl) vectorized and written in assembler. Most of the vectorization is fairly obvious and only the reduction loops contain any obscurity. In order to maintain peak vector efficiency the MVP-9500 reduction loop does a little more work than is strictly necessary an alternative would ruin the vector flow. It is left as an exercise to the determined reader to unravel the full correspondence between Tables XIII and XIV. 

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