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From: Daniel Shahaf <d.s@daniel.shahaf.name>
To: zsh-users@zsh.org
Subject: Re: forcing float arithmetic.
Date: Thu, 25 Mar 2021 01:36:41 +0000	[thread overview]
Message-ID: <20210325013641.GE18178@tarpaulin.shahaf.local2> (raw)
In-Reply-To: <22260ea8-adec-6e16-9250-c2c2ab31fcba@eastlink.ca>

Ray Andrews wrote on Wed, Mar 24, 2021 at 18:12:29 -0700:
> On 2021-03-24 2:59 p.m., Bart Schaefer wrote:
> > On Wed, Mar 24, 2021 at 2:54 PM Roman Perepelitsa
> > <roman.perepelitsa@gmail.com> wrote:
> > > The behavior of zsh in this regard is consistent with C and all languages inspired by it (C++, Java, C# and many, many others). This is really working as intended.
> > Proof:
> > 
> > #include <stdio.h>
> > void main() {
> >   int x = 3, y = 7;
> >   float z = (x/y);
> >   printf("%g\n", z);
> > }
> > 
> Long time since I did any floating point in C, so I'll take you guy's word
> for it.  Final shot would that since one can force the conversion by, say,
> multiplying by 1.0, which is otherwise pointless, one could imagine some
> option whereby the bother is simply not required.
> 
> (( aa = ((2 * nn) - 1) / (nn**2.0) ))
> 
> ... in that case the denominator is not changed in any way, yet if flags
> that the division should be passed as a float.  Seems an awkward way of
> getting the conversion.  How is 2^2 different from 2^2.0 ?  If 'aa' was an
> integer then of course the result must be rounded, but it still seems to me
> the float should receive the actual result.

The «/» operator is defined to perform integer division (discarding the
remainder) when both of its arguments are integers, and floating-point
division otherwise.

That _is_ inconsistent, in a way, since in C it's not possible to
implement a two-argument function that has the same semantics as the «/»
operator for both integral and floating-point types… but that's how it is.

> One of my little whines, nothing of substance. Still one might dream
> of setopt AUTO_FLOAT.

Python 3's division operator always returns floats.

Daniel


  reply	other threads:[~2021-03-25  1:37 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-24 17:19 Ray Andrews
2021-03-24 17:56 ` Bart Schaefer
2021-03-24 21:51   ` Ray Andrews
2021-03-24 21:54     ` Roman Perepelitsa
2021-03-24 21:59       ` Bart Schaefer
2021-03-25  1:12         ` Ray Andrews
2021-03-25  1:36           ` Daniel Shahaf [this message]
2021-03-25  1:45             ` Ray Andrews
2021-03-25  2:37               ` Bart Schaefer
2021-03-25  3:22                 ` Ray Andrews

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