[Matrix-SIG] NumericFix.py

[Andrew P. Mullhaupt]

-----Original Message-----
From: Konrad Hinsen <hinsen@cnrs-orleans.fr>
To: pearu@egoist.ioc.ee <pearu@egoist.ioc.ee>
Cc: matrix-sig@python.org <matrix-sig@python.org>
Date: Monday, November 16, 1998 11:19 AM
Subject: Re: [Matrix-SIG] NumericFix.py


>> The problem is that in order to get sqrt(-1) one has
>> to write sqrt(-1+0j) which, I think, is quite weird.
>
>Well, it may be surprising, but it's the outcome of a design
>decision, not a bug. There are good arguments for making the
>functions behave like they do, once you consider that most
>practical applications do not require complex numbers.


The arguments for automatically widening to complex in an interpreted
language are better.

The two sensible choices are either a domain error (which is what I get with
python) or automatic widening, which is better.

It's not the end of the world that python uses the domain error, though. You
can get around this with try/except.

It all boils down to whether you believe the programmer _expects_ the result
to widen or not.

The consistency of this with the rest of the language has a lot to do with
this expectation. If integer division and floating point division share the
same syntax (in python they do) then since 3/5 is expected to produce 0 and
not 0.6 then the dice have already been rolled.

It's definitely advantageous in scientific computing to make the other
choice, but this is one that would require pervasive modification of python,
and so we're about ten years too late to do anything about it now.

The choice that has been made is not catastrophic, although in some cases
annoying, but shouldn't be reconsidered at this point.

Later,
Andrew Mullhaupt