diff --git a/functions/eigenvalues.m b/functions/eigenvalues.m
new file mode 100644
index 0000000..0819f12
--- /dev/null
+++ b/functions/eigenvalues.m
@@ -0,0 +1,12 @@
+function [ values, err ] = eigenvalues( A, ite, toll )
+
+i=0;
+err = inf;
+while (i < ite) && (err > toll)
+    [q,r] = qr(A);
+    A1= r * q
+    err = norm(diag(A1) - diag(A),inf) / norm (diag(A1),inf);
+    A = A1;
+    i=i+1;
+end
+values = diag(A);
diff --git a/functions/power_method.m b/functions/power_method.m
index 6dc8d1c..1e79c5a 100644
--- a/functions/power_method.m
+++ b/functions/power_method.m
@@ -1,22 +1,22 @@
 
 
-function [v,a] = power_method (U,toll)
+function [vn,a] = power_method (U,toll)
 
 [x,~] = size(U);
 for i=1:x
     v(i)=1;
 end
 v=v';
+vn=v;
 
 err = inf;
 while err > toll
-    
     v1=U*v;
-    v1=v1./norm(v1,inf);
-    err = norm(v1-v,inf);
+    v1n=v1./norm(v1,inf);
+    err = norm(v1n-vn,inf);
     a = v1./v;
     v=v1;
-    
+    vn=v1n;
 end
 
 
diff --git a/samples/similar matrix.m b/samples/similar matrix.m
new file mode 100644
index 0000000..81b25b3
--- /dev/null
+++ b/samples/similar matrix.m	
@@ -0,0 +1,3 @@
+B =  inv(S) * A * S;
+
+A e B sono simili e hanno gli stessi autovalori
\ No newline at end of file