HARP - A SPECIAL-PURPOSE COMPUTER FOR N-BODY PROBLEM

We present the concept of HARP (Hermite AcceleratoR Pipeline), a speci al-purpose computer for solving N-body problem using the Hermite integ rator. A Hermite integrator uses analytically calculated derivatives o f the acceleration, in addition to the acceleration, to integrate the orbit of a particle. lt has a better stability and allows a longer tim e step than does an Adams-Bashforth-Moulton type predictor-corrector s cheme of the same error order. HARP is a specialized computer for this type of Hermite scheme. Its structure is quite similar to GRAPE; the only difference is that it calculates the time derivative of the accel eration, in addition to the acceleration. We are now developing HARP-1 , the first prototype machine with a peak speed of 240 Mflops. The mas sively parallel GRAPE-4 will be based on this HARP architecture. Its s peed will be about 1 Tflops.