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

[Michael Goffioul]

Hi,

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?

Michael.