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From Greg Sterijevski <>
Subject Re: [math] Re: SingularValueDecompositionImpl
Date Fri, 12 Aug 2011 13:39:33 GMT
Thanks! There is an additional method I am moving in. Its the inverse of the
condition number.

    public double getInverseConditionNumber() {
        return singularValues[FastMath.min(m,n) - 1] / singularValues[0];

This addition stems from an issue (MATH-602) I submitted awhile back.
Namely, in cases of rank deficiency the regular condition number will become
undefined. This is not a huge issue, but if you are using condition number
to choose a matrix in some selection routine (say steppwise regression) then
having a somewhat robust criterion might be helpful.

The patch is sitting in the queue.


On Fri, Aug 12, 2011 at 8:16 AM, Gilles Sadowski <> wrote:

> On Thu, Aug 11, 2011 at 04:31:15PM -0500, Greg Sterijevski wrote:
> > At least three with some code I checked in last night. The point is that
> > there is no reason to replicate the same thing over and over again.
> I understand the point.
> I've replaced those 2 occurrences which I detected (revision 1157083).
> Let me know the location of the third one.
> Also, I think that further cleanup is possible (cf. "wantu" and "wantv"
> checks that don't seem very useful).
> Regards,
> Gilles
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