Problem with std::complex::real implementation under MSVC

[John W. Eaton]

On 29-Oct-2008, Michael Goffioul wrote:

| Recently I tried to recompile octave with MSVC and
| notice a compilation error that is specific to MSVC,
| in lo-specfun.cc. Basically, the problem is that MSVC
| does not implement
| 
|   T& real (void)
| 
| but
| 
|   T real (const T& val)
| 
| instead. So for instance, you cannot write something
| like the following
| 
|   y.real () *= expz;
|   y.imag () *= expz;
| 
| In this specific case, you could simply use
| 
|   y *= expz
| 
| because expz is float anyway. And you cannot write
| 
|   y.imag () = 0.0;
| 
| but you could use
| 
|   y = std::complex (y.real (), 0.0);
| 
| I can provide a complete patch, but would such changes
| be acceptable?

It's fine with me.  I wasn't sure about the portability of my recent
changes and I only checked GNU libstdc++ headers.  Sorry about not
doing a more thorough check.

Should we also prefer x.real () over real (x)?  I guess it would be
nice to be somewhat consistent in our usage.

jwe