Why Python 3?

[Terry Reedy]

On 4/20/2014 5:40 PM, Roy Smith wrote:
> In article <mailman.9383.1398012417.18130.python-list at python.org>,
>   Chris Angelico <rosuav at gmail.com> wrote:
>
>> On Mon, Apr 21, 2014 at 2:22 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
>>> When I'm writing a generic average function, I probably don't know whether
>>> it will ever be used to average complex numbers.
>>
>> This keeps coming up in these discussions. How often do you really
>> write a function that generic? And if you do, isn't it doing something
>> so simple that it's then the caller's responsibility (not the
>> function's, and not the language's) to ensure that it gets the right
>> result?
>>
>> ChrisA
>
> Hmmm.  Taking the average of a set of complex numbers has a reasonable
> physical meaning.  But, once you start down that path, I'm not sure how
> far you can go before things no long make sense.  What's the standard
> deviation of a set of complex numbers?  Does that even have any meaning?

One can either calculate variance from the sum of squared distances from 
the mean point, or calculate x and y deviations separately and calculate 
the covariance matrix thereof.

-- 
Terry Jan Reedy