std.complex

[eles]

== Quote from Lars T. Kyllingstad (public at kyllingen.NOSPAMnet)'s
article
> On Tue, 11 May 2010 15:08:07 +0000, eles wrote:
> > Maybe I am wrong, but my feeling is that if the complex numbers
were a
> > native type (like creal&co. are now), then it would have been
possible
> > to have a dedicated formatting (just like %f, %d and %s are) for
> > writefln.
> >
> > Putting the type into the library seems to forbid some very nice
things:
> >
> >  - initializing with "Complex!double z=1+2i" or "Complex!double
z=1+2*i"
> I don't think there will still be a special syntax for complex
literals
> when the built-in types are deprecated.  I'd guess not.  It is,
however,
> likely that creal etc. will be aliases for Complex!real etc.  And
this
> doesn't look that bad:
>   auto z = cdouble(1,2);

My opinion is that it does. Image writing y=(3+2i)^2+z^2*i.

OTOH, the suggestion you made below (see below)...

> >  or or
> > "Complex!double z=2.23*exp(1.107*i)" syntax (which is very
practical) -
> The following does just that, and IMO it looks a lot better:
>   auto z = fromPolar(2.23, 1.107);
> > even in C99 one could write "complex double z=1+2*I" (but "I" is a
> > defined symbol) - instead of "Complex!double(2,3)"
> If you want that, just define
>   immutable I = Complex!float(0, 1);

it is nice. However, I think it should be defined as Complex!real
(0,1);

I hope it will be automatically downsized to Complex!int if the left
value is a Complex!int and so on.

I vote for defining it in std.complex for the folowing reasons:

 - it will enforce coding discipline and standardize code among
libraries and users, the code will be consistent and copy-paste
portable.
 - it is similar to C99, already judged as acceptable for the C
community
 - if such an elementary thing is left to be defined by the
programmer, what long before not using the std.complex module at all?
I mean, as well one could re-define the whole complex library. I
think having std.complex in the standard library is primarily for
standardization and only second for its usefulness (ok, is useful
too, but I want to make a point).

 Also, I think the best is to mimick the functions in the C99
<complex.h>: http://www.opengroup.org/onlinepubs/009695399/basedefs/
complex.h.html

 Me, for one, I prefer writing y=z*conj(z) instead of z=z*z.conj().
OK, maybe is just personal preference.

 OTOH, I feel like maintaining x.re and x.im instead of creal(x) and
cimag(x), since the latter (as defined in C99) are only right-values.

 I have some experience with both C99 complex and with GNU Scientific
Library GSL_COMPLEX. Both have ups and downs, I still prefer to work
with C99, though.

 Also, if we are here, is any way to define ' (apostrophe) for an
(unary) operator? Having z' to mean (z conjugate) would be awesome
(y=z*z'). But maybe is just my Matlab background speaking here. Or
another character (ideas, anyone?... #z, z#, z~ or ~z etc.).

 A note of modesty: I do not try to push it harder than it is
acceptable, but since the complex numbers are just in a major
rewrite, let's try to do it in the best way. We are not constrained
by compatibility/legacy issues.

 Thanks.

 eles