Gauss-Seidel

% Parametros: A, b, X inicial, convergencia, tolerancia

function x = gauss_seidel(A, b, xi, conv, tol)

tic

ox = xi;

tx = ones(1,length(xi));

k=0;

while  max(abs(A*tx' - b)) > tol

sprintf('Iteracao %d... variacao = %0.5g',k, abs(max(ox - tx) / max(tx)))

 sprintf('Maoir erro = %15.5f', max(abs(A*tx' - b)))

ox=tx;

    for i=1:length(b)

        soma1=0;

        for j=1:i-1

            soma1=soma1 + A(i,j)*tx(j);

        end

        soma2=0;

        for j=i+1:length(b)

            soma2=A(i,j)*ox(j);

        end

        tx(i) = (b(i) - soma1 - soma2) / A(i,i);

    end

 k=k+1;

 if abs(max(ox - tx) / max(tx)) > conv

     disp('Algoritmo nao converge!');

     break

 end

if max(abs(A*tx' - b)) > tol

 if abs(max(ox - tx) / max(tx)) == 0

    disp('Algoritmo travou!');

    break

end

end



end

if max(abs(A*tx' - b)) <  tol

    sprintf('Resolvido na iteracao %d', k)

end

toc

erro = (A* tx' - b)'

x = tx;



x_inversao = (inv(A)*b)'