quartiles:=proc(x,m,n)
   local max_val, max_idx, i, j, k, q1, q2, q3,
         m1, m3, n1, n3;
 
   # reorder the array
   for k from m to n-1 do
      max_val:=x[k];
      max_idx:=k;
      for i from k+1 to n do
         if x[i]>max_val then
            max_val:=x[i];
            max_idx:=i;
         fi;
      od;
      x[max_idx]:=x[k]; 
      x[k]:=max_val;
   od;

   print(`The array in decending order`);
   print(eval(x));

   # find the median and index ranges for quartiles
   if type(n-m+1,odd) then
      q2:=x[(n+m)/2];
      m1:=m; n1:=(n+m)/2;
      m3:=(n+m)/2; n3:=n;
   else
      q2:=0.5*(x[(n+m-1)/2]+x[(n+m+1)/2]);
      m1:=m; n1:=(n+m-1)/2;
      m3:=(n+m+1)/2; n3:=n;
   fi;

   # find the 1st/3rd quartile
   if type(n1-m1+1,odd) then
      q1:=x[ (n1+m1)/2 ];
      q3:=x[ (n3+m3)/2 ];
   else
      q1:=0.5*( x[(n1+m1-1)/2]+x[(n1+m1+1)/2] );
      q3:=0.5*( x[(n3+m3-1)/2]+x[(n3+m3+1)/2] );
   fi;

   print(`The 1st, 2nd and 3rd quartiles`);
   print(q1, q2, q3);
   
end;