sort( r, lo, up )

     ArrayToSort r;

     int lo, up;

     {int i, j;

     while (up>lo)  {

          j = lo;

          for ( i=lo; i
               if ( r[i].k > r[i+1].k ) {

                    exchange( r, i, i+1 );

                    j = i;}

          up = j;

          for ( i=up; i>lo; i-- )

               if ( r[i].k < r[i-1].k ) {

                    exchange( r, i, i-1 );

                    j = i;}

          lo = j;

          }

     }