PERFORMANCE OF A QR ALGORITHM IMPLEMENTATION ON A MULTICLUSTER OF TRANSPUTERS

Some results of an implementation of the QR factorization by Household er reflectors, on a multicluster transputer system with distributed me mory are presented, that show how important is the communication time between processor in the performance of the algorithm. The QR factoriz ation was chosen as test method because it is required for many real l ife applications, for instance in least squares problems. We use a ver sion of Householder transformation that is the basis for numerically s table QR factorization. The machine used was the MultiCluster 2 model of Parsytec which is distributed memory system with 16 Inmos T800 proc essors. The Hellos operating system was chosen because it provides tra nsparency in CPU management. However it limits the sets of connecting topologies to be used. The results are presented in terms of speedup a nd efficiency, showing the importance of the communication time on the total elapsed time.