complex number support

[Nick Treleaven]

On Sunday, 15 February 2026 at 21:04:17 UTC, Timon Gehr wrote:
> On 2/9/26 12:20, Quirin Schroll wrote:
>> 
>> If you want to make D’s imaginary and complex types perfect, 
>> allow for an implicit conversion from floating point types to 
>> complex types that are bigger. I can’t remember how often I’ve 
>> written `+ 0i`.
>
> Apparently that used to exist and was removed:
> https://forum.dlang.org/post/di2p73$2mgj$1@digitaldaemon.com

I don't think the logic below still applies:
```
real sin(real x)

-- (in user code) --

real w = sin(0.25);
float f = somefunc(); // maybe it's in a C library

real w2 = sin(f);

--------------------

Now we would like to add a complex sine function to std.math
creal sin(creal x)
```

The float argument would match both the real and the creal 
parameter overloads as before. But now we have [partial 
ordering](https://dlang.org/spec/function.html#partial-ordering) 
which would find real converts to creal, but creal still would 
not convert to real, so real is the more specialized overload. So 
`sin(f)` would call the `sin(real)` overload even if float did 
convert to cfloat.