function [xnew,force,tens] = iteraplot (xx,alfa,beta)
global nb nv barras restric massa x0

[force tens] = res(xx);
err=norm(force,inf)

%%mat=-eye(2*nv);
mat=matdif(xx,0.001);

dk=-mat\force;

vk=alfa*dk;
dif=norm(vk,inf)
xnew = xx+vk;

uu=xnew-x0
%%pause;
%%load("alfa.txt");
for i=1:nb
	xyloc(1,1) = x0(2*barras(i,1)-1)+beta*uu(2*barras(i,1)-1);
	xyloc(1,2) = x0(2*barras(i,1))+beta*uu(2*barras(i,1));
	xyloc(2,1) = x0(2*barras(i,2)-1)+beta*uu(2*barras(i,2)-1);
	xyloc(2,2) = x0(2*barras(i,2))+beta*uu(2*barras(i,2));
        plot(xyloc(:,1),xyloc(:,2));
        hold on;
	xyloc(1,1) = x0(2*barras(i,1)-1);
	xyloc(1,2) = x0(2*barras(i,1));
	xyloc(2,1) = x0(2*barras(i,2)-1);
	xyloc(2,2) = x0(2*barras(i,2));
        plot(xyloc(:,1),xyloc(:,2));
        hold on;
end
axis([-1 2 -1 5]);
hold off;
%%pause;
end