X=[102,109,105,103,108,105,115,118,116,113]; Y=[110,113,115,103,105,108,104,108,113,118]; Z=[15;18;19;17;21;15;20;15;17;22]; Xi=X-[110,110,110,110,110,110,110,110,110,110]; Yi=Y-[110,110,110,110,110,110,110,110,110,110]; P=[]; for i=1:10; di=sqrt(Xi(i)^2+Yi(i)^2); pi=1/di^2; P=[P;pi]; end; P=diag(P); M=[]; for i=1:10; Mi=[Xi(i)^2,Xi(i)*Yi(i),Yi(i)^2,Xi(i),Yi(i),1]; M=[M;Mi]; end XX=inv(M'*P*M)*M'*P*Z