I have been trying to run the simulation of GW150914 given in gallery .The simulation ran succesfully .However I am only getting a partial waveform .The merger and the ringdown phase is not being captured .I am attaching both the waveform and a gnuplot showing the completing of merger . There is also another doubt I have .In the gallery while creating the job for this simulation there is a command called --define N which  is set to 28 .Could someone tell me whats the purpose of that and help me understand whats going wrong ?