On 12/12/13 6:31 AM, Don wrote:
On Wednesday, 11 December 2013 at 21:00:19 UTC, Joseph Rushton Wakeling
wrote:
On 11/12/13 13:44, Simen Kjærås wrote:
I've tried to figure out good ways to add some sorely-needed implicit
conversions to the language, but I'm sure there are details that need
to be
ironed out. In other words - destroy!
Since you brought up std.complex: some of the issues here are subtle.
For example, it's appropriate to allow implicit conversion from
numerical => Complex (although this can be done fairly readily by just
calling complex(x) where x is a numerical type); it's also appropriate
to allow implicit conversion from Imaginary => Complex; but it'd be
wrong to allow implicit conversion from numerical => Imaginary.
Conversely, I'm not certain whether it'd be appropriate to allow
implicit conversion Complex => numerical or Complex => Imaginary, even
if the imaginary or real parts respectively were zero.
I don't think Imaginary should exist at all. Mathematically, it's nonsense.
It's exactly like defining a NegativeInteger. It has horrible
properties, such as, it's not closed under multiplication!
I don't think there are many applications for pure imaginary numbers, I
tried to come up with one but failed. Kahan only provides one example in
his paper, and it's contrived. It eliminates one subtlety but introduces
far more. In practice it is always far better to just operate directly
on the real and imaginary parts.
Great. I'm all for keeping it simple :o). Can you fix Kahan's example
(or class of examples) with a glorious hack and call it a day?
Andrei
