Complex literals (was Re: I am never going to complain about Python again)

[Oscar Benjamin]

On 11 October 2013 10:35, David <bouncingcats at gmail.com> wrote:
> On 11 October 2013 12:27, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
>> On Fri, 11 Oct 2013 00:25:27 +1100, Chris Angelico wrote:
>>
>>> On Fri, Oct 11, 2013 at 12:09 AM, Roy Smith <roy at panix.com> wrote:
>>>> BTW, one of the earliest things that turned me on to Python was when I
>>>> discovered that it uses j as the imaginary unit, not i.  All
>>>> right-thinking people will agree with me on this.
>>>
>>> I've never been well-up on complex numbers; can you elaborate on this,
>>> please? All I know is that I was taught that the square root of -1 is
>>> called i, and that hypercomplex numbers include i, j, k, and maybe even
>>> other terms, and I never understood where j comes from. Why is Python
>>> better for using j?
>>
>> Being simple souls and not Real Mathematicians, electrical engineers get
>> confused by the similarity between I (current) and i (square root of -1),
>> so they used j instead.
> [...]
>> <wink>
>
> No, electrical engineers need many symbols for current for the same reason
> that eskimos need many words for snow :) [*]

There are many other letters in the Roman alphabet to choose from
though. In particular the study of complex numbers and the choice of i
for sqrt(-1) predates most of the study of electricity and the use of
I to denote current (it was previously called C in English texts).
Obviously I understand that that's all history and once conventions
are so widely adopted it's pointless to change them but it's good to
have common notation for the elementary parts of maths. If someone
tried to explain why their field couldn't use π for the circumference
of a unit circle I would suggest that they adjust the other parts of
their notation not π (there are other uses of π.

Truthfully I've now spent more time with engineers than
physicists/mathematicians and find it natural to switch between i and
j depending on who I'm talking to and what I'm talking about. It's
still confusing for students though when I switch between conventions
to use whichever is standard for a given subject.


Oscar