function [x1,iter] = template_im_2(a,b,alpha,x0,tol,maxiter)
%%criterio: fermati quando err<=tol o iter>maxiter
%%quindi: lavora quando err>tol e iter<=maxiter
err=inf;
iter=0;
n=length(b);
x1=zeros(n,1);
b=alpha*b;
a=alpha*a;
a=speye(n)-a;
while(err>tol & iter<=maxiter)
    x1=a*x0+b;
    err=norm(x1-x0, inf)/norm(x1,inf);
    x0=x1;
    iter=iter+1;
end
end