Re: large sparse matrix

[Carlo de Falco]

On 1 Sep 2009, at 10:04, Carlo de Falco wrote:

> 2009/9/1 Carlo de Falco <address@hidden>:
>
> > > Also, what does the code
> > >
> > > [R, p, q] = chol(A);
> > > nnz(R)
> >
> > > work for Octave and Matlab?
> >
> > I tried this in Octave, after 30 min it did not finish yet...
> > I will only be able to try it on Matlab tomorrow.
> >
> > > If so what is the value of NNZ of the factorization in both cases.
>
> I killed the Octave after it had been running more than one hour and
> produced no result.
> In Matlab it ran in less than a second and the result was:
>
> > > [R,p,q]=chol(A);
> > > nnz (R)
> ans =
>     1368019
> > > issparse (R)
> ans =
>     1
> > > nnz(R)/prod(size(A))
> ans =
>     7.035863106552923e-03

oops, what I actually meant to show here was

>> nnz(R)/prod(size(R))
ans=
   1.407374482251814e-02

> Thanks,
c.