codergirl / n_body_simulator Goto Github PK

   
   This program is a simple simulation of the N-body problem.
   It takes two parameters,
       NUM_BODIES - the number of bodies to simulate
       NUM_TIME_STEPS - the number of times to repeat simulation
       
   Please run by going
       mpiexec -n NUM_THREADS ring NUM_BODIES NUM_TIME_STEPS

   Please note that if NUM_BODIES does not divide evenly into NUM_THREADS,
   there will be elements at the end of the arrays which remain uninitialized.
   
   I use a ring to communicate the positions of the bodies. I wrap the 
   positions of the bodies. I also do not let the distance between bodies
   get too small, to prevent the forces from getting huge.
   
   Note. Every process has a copy of an array with the positions of all
   other bodies. My implementation retains consistent array indexing 
   across all the processes. The ordering of the particles however does 
   not matter, and this method reqiures extra calculations which aren't
   necessary. However it was easier to ensure that my messages were being
   passed correctly by implementing it this way.