tikhonov(U​,s,V,b,lam​bda,x_0) Error

I cant get tikhonov(U,s,V,b,lambda,x_0) to run even for a simple example given in Christian Hansen Package. Here it is including the error:

EDU>> clear
EDU>> A= [
0.15  0.1
0.16  0.1
2.02  1.3
];
b =[
0.27
0.25
3.33];

x=[
1;1
];
b=A*x;

db=[.01; -.032; .01];
b1=b+db;
x2=pinv(A)*b1;
x_0=[0;0];
lambda=0.001;

[U,s,V]=svd(A);

[x_lambda,rho,eta]=tikhonov(U,s,V,b,lambda,x_0);
[x_lambda,rho,eta]=tikhonov(U,s,V,b1,lambda,x_0);

Index exceeds matrix dimensions.

Error in tikhonov (line 66)
  if (nargin==6), omega = V\x_0; omega = omega(1:p); end

%******************************************************************

When I try it on

A=hilb(12)
x=[1;1;1;1;1;1;1;1;1;1;1;1

after computong

b=A*x

and

U,s,V
x_0=[0;0;0;0;0;0;0;0;0;0;0;0]

I get NaN for output.

Not sure what I'm doing wrong. Can someone give a simple example that runs?

Thank you

[ANA ROSHAN]

VERY GOOD

[ANA ROSHAN]

Answer 1

[Daniel Vasilaky]

OK, I know what I was doing wrong. Instead of the full SVD I should have used the compact SVD, namely csvd. In a compact svd the columns of U and the rows of V’ are computed only for non-zero singular values. The zeroes in the full svd were causing the errors. Apologies for my ignorance.

Answer 2

[Yishi]

That works, I did not know either, but thanks for posting this comment