[Numpy-discussion] matrix norm
jason-sage at creativetrax.com
Mon Oct 22 16:09:39 EDT 2012
On 10/22/12 3:03 PM, Pauli Virtanen wrote:
> Jason Grout <jason-sage <at> creativetrax.com> writes:
>> I think we've established that the other software mentioned does indeed
>> use the spectral norm by default. I'm still curious: what was the
>> reason for breaking with the norm (pun intended :)? Any chance that in
>> a (probably far distant) future release, the norm default could be
>> changed to conform with matlab/octave/mathematica's view of the world?
>> It's not a huge deal to me now that I know to watch out for it, but it
>> did just bite me and a student a few times.
> The trail leads to here:
> Seems like the chances of learning the reason why this change was done
> are pretty slim.
Thanks for tracking this down. It looks like the default used to be the
spectral norm. I guess there still is a question of if it is possible
to change it back at this point.
FYI, in Sage, we were following the numpy convention (default =
Frobenius norm) for numerical matrices, but we are now switching the
default to be the spectral norm .
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