public static long pop_array(long[] arr,int wordOffset,int numWords){
  long popCount=0;
  for (int i=wordOffset, end=wordOffset + numWords; i < end; ++i) {
    popCount+=Long.bitCount(arr[i]);
  }
  return popCount;
}

public static long pop_array ( long [ ] arr , int wordOffset , int numWords ) { long popCount = 0 ; for ( int i = wordOffset , end = wordOffset + numWords ; i < end ; ++ i ) { popCount += Long . bitCount ( arr [ i ] ) ; } return popCount ; }
returns the number of set bits in an array of longs .
