// rozwiazanie przy pomocy calki

wi=[0.1012285362,0.2223810344,0.3137066458,0.3626837833,0.1012285362,0.2223810344,0.3137066458,0.3626837833];
xi=[0.9602898564,0.7966664774,0.5255324099,0.1834346424,-0.9602898564,-0.7966664774,-0.5255324099,-0.1834346424];


function d=f(x,y)
  d=abs(x-y);
endfunction

suma=0;
for i=1:8
  for j=1:8
    suma = suma + wi(i)*wi(j)*f(xi(i),xi(j));
  end;
end;
disp(suma);

// rozwiazanie doswiadczalne

disp([sum(abs((rand(1d6,1)*2-1)-(rand(1d6,1)*2-1)))/1d6])