From: "G.B." <bauhaus@futureapps.invalid>
Subject: Re: Incompatible types for array conversion
Date: Wed, 22 Jul 2015 16:22:35 +0200
Date: 2015-07-22T16:22:35+02:00 [thread overview]
Message-ID: <moo8sh$rof$1@dont-email.me> (raw)
In-Reply-To: <d19iapFknp1U1@mid.individual.net>
On 22.07.15 14:57, hreba wrote:
>> That's exactly turning the accidental relationship due to
>> assumed similarity of component types into a relationship
>> of Direction and Position that does not exist in the physical world.
>> Type error ;-) caused by assumptions about the implementation
>> dictating specification.
>
> Wrong. It is common in physics to multiply a dimensionless direction
> vector (typically a unit vector) with a scalar of some dimension
> (length, velocity, whatever).
OK, naming issue then. If the Position can be interpreted
as a Point determining a direction, that's an excuse
for scalar multiplication with subtype constraints, at
the level of implementation, or some conversions.
A comment would reduce condescension and unforeseen
misunderstanding by non-peers. (If that's wanted.)
Proper types and maybe operations would look cleaner
to me.
> I declared vectors of real types because I need to describe real
> mathematical numbers (classical continuous physical quantities). There
> might be a reason to rethink the solution in future, but in a way
> different to your suggestion: my current implementation allows
> multiplication of a Position variable with a Length variable resulting
> in a Position vector. The physically correct dimension would be length
> squared instead of length. Up to now I can live without that.
That's one reason to toss assumptions: if it is not just a scalar
multiplication (respecting units), and you don't use SI aspects,
another type can do. There are packages for this, I believe
Christoph Grein has some online.
next prev parent reply other threads:[~2015-07-22 14:22 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-22 1:19 Incompatible types for array conversion hreba
2015-07-22 5:20 ` Niklas Holsti
2015-07-22 7:13 ` Simon Wright
2015-07-22 7:41 ` Niklas Holsti
2015-07-22 12:32 ` Simon Wright
2015-07-27 23:12 ` Randy Brukardt
2015-07-22 13:00 ` hreba
2015-07-22 13:22 ` hreba
2015-07-22 17:50 ` Niklas Holsti
2015-07-22 19:02 ` Dmitry A. Kazakov
2015-07-22 6:49 ` Georg Bauhaus
2015-07-22 12:57 ` hreba
2015-07-22 14:22 ` G.B. [this message]
2015-07-23 13:21 ` hreba
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