Optimisation of the Numerical Electromagnetics Code on a four-processor Cray X-MP computer

A standard moment-method electromagnetic field computation program (the Numerical Electromagnetics Code) was subjected to a series of modifications to improve its execution speed on a vector processing computer with four pipelines. For test problems involving computation of the near field of an array of log-periodic antennas speed improvements of up to eight times were achieved by a combination of the following techniques: code reordering to maximise vectorisability; microtasking of interaction matrix solution; and macrotasking of matrix filling and near-field computation. Micro and macrotasking are alternative techniques for scheduling of the parallel processors: the techniques required were substantially architecture-dependent, thus limiting portability of the revised code. The maximum speed achieved was one-seventh of the theoretical maximum for the computer