Linear least squares solutions by Householder transformations with column pivoting on a parallel machine

Using Householder transformations to solve linear least squares problems is very efficient. We have found a computational form especially suitable for BBN Butterfly, a parallel computer. We modified the algorithm for parallel processing using various constructs from the BBN Mach 1000 system. We were able to obtain a speed-up of 3 with 4 processors, and 3.83 with 6 processors for M=1000, and N=200, which means Ep=75% and 64% CPU utilization. We conclude that our algorithm realized a reasonably good speedup with a moderate number of processors.