http://d.puremagic.com/issues/show_bug.cgi?id=6154

           Summary: std.math.abs on std.complex numbers too
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: Phobos
        AssignedTo: nobody@puremagic.com
        ReportedBy: bearophile_hugs@eml.cc


--- Comment #0 from bearophile_hugs@eml.cc 2011-06-14 05:03:13 PDT ---
I'd like std.math.abs to perform what std.complex.Complex!T.abs does. So I will be able to use it functionally (currently std.math.abs is able to work on the built-in complex numbers too). This means I'd like this code to work:

import std.stdio, std.math, std.algorithm, std.complex;
void main() {
    alias Complex!double C;
    C[] array2 = [C(1,2), C(2,4)];
    auto m2 = map!abs(array2);
    writeln(m2);
}



In DMD 2.053 similar code with built-in complex numbers works:

import std.stdio, std.math, std.algorithm;
void main() {
    cdouble[] array1 = [1+2i, 2+4i];
    auto m1 = map!abs(array1);
    writeln(m1);
}


In DMD 2.053 if you want to do the same with complex numbers you need to write:

import std.stdio, std.math, std.algorithm, std.complex;
void main() {
    alias Complex!double C;
    C[] array2 = [C(1,2), C(2,4)];
    auto m2 = map!((c){ return c.abs(); })(array2);
    writeln(m2);
}

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kennytm@gmail.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |kennytm@gmail.com


--- Comment #1 from kennytm@gmail.com 2011-06-14 06:26:44 PDT ---
(In reply to comment #0)
> In DMD 2.053 if you want to do the same with complex numbers you need to write:
> 
> import std.stdio, std.math, std.algorithm, std.complex;
> void main() {
>     alias Complex!double C;
>     C[] array2 = [C(1,2), C(2,4)];
>     auto m2 = map!((c){ return c.abs(); })(array2);
>     writeln(m2);
> }

    auto m2 = map!`a.abs()`(array2);

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--- Comment #2 from bearophile_hugs@eml.cc 2011-06-14 10:01:24 PDT ---
(In reply to comment #1)

>     auto m2 = map!`a.abs()`(array2);

Right. But std.math.abs has to work on complex numbers too, as before, for polymorphism, and for a serious integration of complex numbers in Phobos.

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Don <clugdbug@yahoo.com.au> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |clugdbug@yahoo.com.au


--- Comment #3 from Don <clugdbug@yahoo.com.au> 2011-06-14 11:03:40 PDT ---
(In reply to comment #2)
> (In reply to comment #1)
> 
> >     auto m2 = map!`a.abs()`(array2);
> 
> Right. But std.math.abs has to work on complex numbers too, as before,

No, it does not, and will not.
BTW that approach would lead to executable bloat.

> for polymorphism, and for a serious integration of complex numbers in Phobos.

No. This is what overload sets are for.

Complex must not be given special treatment ahead of user-defined types. Otherwise, user-defined types become second-class citizens.

(std.math.abs is a bit of a problem at the moment, there are a couple of functions in std.math which have range versions, which IMHO have no business being in there).

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--- Comment #4 from kennytm@gmail.com 2011-06-14 13:22:08 PDT ---
(In reply to comment #2)
> (In reply to comment #1)
> 
> >     auto m2 = map!`a.abs()`(array2);
> 
> Right. But std.math.abs has to work on complex numbers too, as before, for polymorphism, and for a serious integration of complex numbers in Phobos.

Right, but why must it be std.math.abs? Putting the free function as std.complex.abs works too.

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--- Comment #5 from bearophile_hugs@eml.cc 2011-06-15 13:04:17 PDT ---
(In reply to comment #4)

> Putting the free function as std.complex.abs works too.

OK.

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Lars T. Kyllingstad <bugzilla@kyllingen.net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |bugzilla@kyllingen.net
         Resolution|                            |FIXED


--- Comment #6 from Lars T. Kyllingstad <bugzilla@kyllingen.net> 2013-08-04 05:51:12 PDT ---
std.complex.abs() was added in May 2012.

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