Geometry Boost List: Re: [geometry] Andoyer geographic distance

Subject: Re: [geometry] Andoyer geographic distance
From: Adam Wulkiewicz (adam.wulkiewicz_at_[hidden])
Date: 2014-11-11 18:49:55

Hi,

2014-11-11 1:53 GMT+01:00 Branimir Betov <bbetov_at_[hidden]>:

> Hi,
>
> I am trying to work with boost 1.57 and also I've got the
> geometry.extensions.gis from the develop branch. I am using geographic cs.
> Looking at extensions\gis\geographic\strategies\andoyer.hpp I think there
> is a problem with one of the constructors:
>
>     explicit inline andoyer(RadiusType f)
>         : m_ellipsoid(f)
>     {}
>
> I think should be:
>
>     explicit inline andoyer(RadiusType f)
>         : m_ellipsoid(f*, f*)
>     {}
>
> (note the second radius passed to m_ellipsoid). Otherwise it chooses the
> incorrect constructor for the ellipsoid and distances are incorrect.
>
>
I'm not entirely sure what's the purpose of this ctor and one-argument ctor
of ellipsoid. I'd say that the intention was to create a "unit" ellipsoid
with radius=1 and flattening f, but there is an error in the ellipsoid ctor
(it doesn't set B, only A and F). There is a reference to a unit sphere
(not ellipsoid) in the comment:

// Unit sphere  ellipsoid(T const& f)  : m_a(1.0)  , m_f(f)  {}
https://github.com/boostorg/geometry/blob/develop/include/boost/geometry/extensions/gis/geographic/detail/ellipsoid.hpp

I plan to clean this code and move from extensions in the near future. I
think that this ctor could just dissapear. In the meanwhile I may just fix
it by setting B properly.

> Sorry for posting it in the groups - I am not sure what the proper way to
> submit a patch is.
>
>
This group is a right place for such discussion :)

A patch could be sent to this group or proposed directly on GitHub. I
personally prefer the latter. Here is a tutorial:
https://github.com/boostorg/geometry/wiki/Contribution-Tutorial

Regards,
Adam