Re: [boost] Determining interest: Pure imaginary number library

Subject: Re: [boost] Determining interest: Pure imaginary number library
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2012-02-29 17:57:25

Le 29/02/12 13:36, Matthieu Schaller a écrit :
> Dear all,
>
> A few months ago I proposed to add an imaginary number class to boost 
> in order to extend the std::complex class and improve performance when 
> computations involving pure imaginary numbers are involved.  Some of 
> you showed some interest and proposed some possible improvements, the 
> main one being to actually replace the std::complex class by a 
> boost::complex and boost::imaginary pair of classes in order for all 
> operations to be truly symmetric and closer to the mathematical notation.
>
> I have applied these modifications and the code now corresponds to an 
> extended version of Thorsten Ottosen's n1869 proposal 
> (http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2005/n1869.html)
>
> The sources and documentation are available here : 
> http://code.google.com/p/cpp-imaginary-numbers/
> They can be retrieved via the SVN repository or downloaded directly as 
> an archive.
>
> The archive contains the complex.hpp header, a performance test, an 
> accuracy test and two examples showing the benefits of the imaginary 
> numbers in "downscaled" real life situations. I have tentatively 
> embedded everything in the boost::math namespace in order to look for 
> potential naming conflicts between my code and the existing boost ones.
>
> I would be happy to hear any comment from your side and still hope 
> that this work is of some interest to you.
>
Hi,

glad to see you have an almost complete library.

I don't like the comparison between reals and imaginary just because 
they share a value.

/// Returns true if x does not equal y
template<typename T>
inline bool operator!=(const imaginary<T>& x, const T& y)
{
     return x.imag() != T(0.) || y != T(0.);
}

I think that I found a copy/paste issue in

template<typename T>
inline complex<T> conj(const complex<T>& x)
{
     return imaginary<T>(x.real(), -x.imag());
}

The line should be
     return complex<T>(x.real(), -x.imag());

I would be great if you can ensure that every function has been tested 
at least once ;-)

I guess you could request the library to be added on the review schedule.

Best,
Vicente