Re: Saving data loses information?

[Olaf Till]

On Sat, Nov 02, 2013 at 01:49:43AM +0200, Jose wrote:
> Hello.
> 
> I have a particular case of a covariance matrix with a large
> condition number, whose inverse is problematic
> ---
> debug> eig(cholinv(cov_b));
> error: eig: EIG: matrix contains Inf or NaN values
> debug> any(any(isnan(cov_b)||isinf(cov_b)))
> ans = 0

You should use '|', not '||'.

> debug> cond(cov_b)
> ans =  1.0901e+06
> ---
> I saved the matrix in a file using the binary option, and to my
> surprise, when loaded into another freshly opened octave session, I
> can execute eig(cholinv(cov_b)) with no problems.
> 
> Could it be the cause of this is that the saving and loading of the
> data is not 100% accurate? Is there any other possibility?

With the binary option, saving and reloading should be '100 %
accurate', at least on the same type of machine.

If it isn't, you should provide a bug report, giving your Octave
version, type of machine, and exactly all commands (including those
for save and load). You should also report the result of

any ((isnan (cov_b) | isinf (cov_b))(:))

before and after re-loading (note the use of '|', not '||').

Olaf

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