On Tue, 18 May 2021 at 16:55, Martin Teichmann
<martin.teichm...@gmail.com> wrote:
>
> Hi Paul,
>
> > > I'd actually prefer to write (m*v**2)/2. Or (m/2)*v**2. But those
> > wouldn't work, the way you describe your proposal. And I'd be very
> > concerned if they behaved differently than 1/2 * m * v**2...
>
> Sure they do work, and they work exactly the same way. That is acually the
> point: currently 1/2 * m * v**2 is not the same as (m/2) * v**2 (in sympy,
> that is), with my proposal it would be exactly the same (again, from my
> prototype, not fake):
>
> >>> m, v, r = symbols("m v r")
> >>> 1/2 * m * v**2
> m*v**2/2
> >>> (m/2) * v**2
> m*v**2/2
> >>> (m * v**2) / 2
> m*v**2/2
> >>> 4/3 * pi * r**3
> 4*pi*r**3/3
But *not* in sympy, in normal Python, if m == 1 and v == 1, then 1/2 *
m * v**2 is 0.5 (a float) currently, as is (m/2) * v**2. But in your
proposal, the former will be a float/fraction hybrid, whereas the
latter will be a float.
And what about
x = 1
a = 1/3
b = x/3
a == Fraction(1,3)
b == Fraction(1,3)
a == b
Currently these are False, False, True. You'll change that to True,
False, True and you've now broken the idea that things that are equal
should compare the same to a 3rd value.
Never mind. At the end of the day, I simply think your proposal is not
viable. We can argue details all day, but I'm not going to be
persuaded otherwise.
Paul
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