Body body;
double[] dpos = new double[nDim];
while (data.bodies_there < data.nbody) {
gBody = bodyTab[data.bodies_there++];
body = (Body) gBody.open( "w" );
MULVS(dpos, body.vel, dtime);
ADDV(body.pos, body.pos, dpos);
try{
gBody.release();
} catch( AlephException e ){}