Re: new snapshot?

[Michael D. Godfrey]

On 2/26/10 10:15 AM, Jaroslav Hajek wrote:
> Are you sure? This is exactly the opposite of what I get. Sometimes
> the assert fails with
>
> !!!!! test failed
> assert (s (k:-1:1),s2,1e-10) expected
>     38.060
>     38.060
>     38.034
>     38.034
>     38.015
>     38.015
>     38.004
> but got
>     38.060
>     38.034
>     38.034
>     38.015
>     38.015
>     38.004
>     38.004
> maximum absolute error 0.0263523 exceeds tolerance 1e-10
>
> and the latter result is correct, AFAIK.
>
>    
The latter result is s2  in the test.  This is what I get too.  s2, 
computed from:
[u2,s2,v2,flag] = svds(a,k,0);
s2 = diag(s2);
is correct.  It is the "expected" vector that is wrong.  This comes from:
a = 
sparse([3:n,1:n,1:(n-2)],[1:(n-2),1:n,3:n],[ones(1,n-2),0.4*n*ones(1,n),ones(1,n-2)]);
[u,s,v] = svd(full(a));
s = diag(s);
[dum, idx] = sort(abs(s));
s = s(idx);

Agree?

Michael