inconsistent condition numbers from cond, det, inv functions

[Ben Abbott]

On Thursday, February 07, 2008, at 08:09AM, "Rolf Fabian" <Rolf.Fabian at gmx.de> wrote:
>
>Ben Abbott wrote:
>> 
>> On Feb 7, 2008, at 7:00 AM, Rolf Fabian wrote:
>> 
>>> Ben, what' s the result for 1./cond(y) ?
>>> Does Matlabs cond() have a similar argument 'p' too?
>> 
>> Yes!
>> 
>> Ben
>
>Thanks Ben. From your results I conclude that MatLab
>is actually doing something very similar than I did for my
>condh-function. I personally have good reasons not to
>send any code any more to any Octave list. So, if you like,
>make jwe happy by sending him a patched version of 'cond.m'
>implementing a 2nd argument p which defines the mode of
>(both) calls to 'norm.m'. In order to conform to ML, the default
>mode should be p=2 as long as input matrix is regular (non-singular).
>
>I've no idea why the ML-result for the 1st (singular) testmatrix x
>from cond() differs from the 2-norm algorithm. This needs further
>test with ML using singular input to cond(), but ML is not available
>for me.
>
>Rolf Fabian

Rolf, 

I happy to help out. Can you email me the modified files?

Ben