octave:2> A=toeplitz([-2 1 0 0])
A =

  -2   1   0   0
   1  -2   1   0
   0   1  -2   1
   0   0   1  -2

octave:3> eig(A)
ans =

  -3.61803
  -2.61803
  -1.38197
  -0.38197

octave:4> potenzefailed(A,1e-8,100)
x =

   3
   4
   4
   3

ans = -2.6180
octave:5> potenzefailed(A,1e-12,100)
x =

   3
   4
   4
   3

ans = -2.6180
octave:6> potenzefailed(A,1e-14,100)
x =

   3
   4
   4
   3

ans = -2.6180
octave:7> A
A =

  -2   1   0   0
   1  -2   1   0
   0   1  -2   1
   0   0   1  -2

octave:8> sum(abs(A),2)
ans =

   3
   4
   4
   3

octave:9> sum(abs(A))
ans =

   3   4   4   3

octave:10> ls
octave:11> potenze(A,1e-14,100)
error: `maxit' undefined near line 19 column 38
error: evaluating binary operator `<' near line 19, column 36
error: evaluating binary operator `&' near line 19, column 28
error: while: error evaluating conditional expression
error: called from `potenze' in file `/home/accounts/altri/caliari/aa0809/calcolo_numerico/autovalori/potenze.m'
octave:11> potenze(A,rand(4,1),1e-14,100)
ans = -3.6180
octave:12> potenze(A,rand(4,1),1e-14,100)
ans = -3.6180
octave:13> potenze(A,rand(4,1),1e-14,100)
ans = -3.6180
octave:14> potenze(A,rand(4,1),1e-14,100)
ans = -3.6180
octave:15> potenze(A,[3 4 4 3]',1e-14,100)
ans = -2.6180
octave:16> w=[1,2,3,4]'
w =

   1
   2
   3
   4

octave:17> w*w'
ans =

    1    2    3    4
    2    4    6    8
    3    6    9   12
    4    8   12   16

octave:18> A
A =

  -2   1   0   0
   1  -2   1   0
   0   1  -2   1
   0   0   1  -2

octave:19> [lambda_1,x]=potenze(A,rand(4,1),1e-8,100)
lambda_1 = -3.6180
x =

   0.37171
  -0.60148
   0.60152
  -0.37179

octave:20> norm(x)
ans =  1
octave:21> deflaziona(A,x)
warning: time stamp for `/home/accounts/altri/caliari/aa0809/calcolo_numerico/autovalori/deflaziona.m' is in the future
B =

  -3.6180e+00   5.9581e-05  -1.2838e-05  -1.5437e-05
   5.9581e-05  -2.4317e+00   4.7433e-01   3.2488e-01
  -1.2838e-05   4.7433e-01  -5.1686e-01   8.3336e-02
  -1.5437e-05   3.2488e-01   8.3336e-02  -1.4334e+00

ans =

  -2.431654   0.474333   0.324878
   0.474333  -0.516863   0.083336
   0.324878   0.083336  -1.433449

octave:22> [lambda_1,x]=potenze(A,rand(4,1),1e-14,100)
lambda_1 = -3.6180
x =

   0.37175
  -0.60150
   0.60150
  -0.37175

octave:23> deflaziona(A,x)
warning: time stamp for `/home/accounts/altri/caliari/aa0809/calcolo_numerico/autovalori/deflaziona.m' is in the future
B =

  -3.6180e+00  -6.4799e-08   1.3959e-08   1.6793e-08
  -6.4799e-08  -2.4317e+00   4.7424e-01   3.2493e-01
   1.3959e-08   4.7424e-01  -5.1682e-01   8.3347e-02
   1.6793e-08   3.2493e-01   8.3347e-02  -1.4335e+00

ans =

  -2.431664   0.474244   0.324935
   0.474244  -0.516824   0.083347
   0.324935   0.083347  -1.433477

octave:24> diary off