function khi2_lu=extraction(tabTheo,alpha)
tab_loi_khi2=zeros(101,22);
tab_loi_khi2(:,1)=(0:100);
tab_loi_khi2(1,17)=0,95;
tab_loi_khi2(1,19)=0,99;
[nl,nc]=size(tab_theo);
degre_liberte=(nl-1)*(nc-1);
for i=2:22
   if tab_loi_khi2(1,i)==(1-alpha)
      indicej=i;
      break;
   end
end
for i=2:101
   if tab_loi_khi2(i,1)==degre_liberte
      indicei=i;
      break;
   end
end
khi2_lu=tab_loi_khi2(indicei,indicej);