//Calculo matriz residuos R
        for (i = 0; i < N; ++i) {
            for (j = 0; j < N; ++j) {
                aux = fabs(I[row[i]*N+j] - A_AI[i*N+j]);
                R[row[i]*N+j] = ( aux <= DBL_EPSILON) ? 0 : I[row[i]*N+j] - A_AI[i*N+j];
            }
        }

        soma = 0.0;
        temp_begin = timestamp();
        for (i = 0; i < N*N; ++i) {
            soma += R[i] * R[i];
        }
        r[l] = fabs(sqrt(soma));