Re: [eigen] cross product with complex vectors

[Christoph Hertzberg <chtz@xxxxxxxxxxxxxxxxxxxxxxxx>]

Here is a related bugzilla entry:

http://eigen.tuxfamily.org/bz/show_bug.cgi?id=944

Short story: We can't just change our API here, but you can use this as 
a workaround:

  a.cross(b.conjugate());


Christoph


On 2018-07-16 13:35, Orell Garten wrote:
> Hi
>
> I was wondering whether the implementation of the cross product for
> complex vectors [1] is correct.
>
> Assume I have two vectors of type Vector3cd which hold a=(0,0,1) and
> b=(0,1+i,0). I do a.cross(b) and would expect to get (-1-i,0,0) but get
> (-1+i,0,0) as a result.
>
> I think the formula in [1] should be (a + ib) x (c x id) = (a x c - b x
> d) + i (a x d + b x c) but maybe I am wrong.
>
> It would be great if somebody could provide some sanity check or the
> reasoning behind [1].
>
> Thanks for helping,
> Orell
>
> [1]
> http://eigen.tuxfamily.org/dox/group__Geometry__Module.html#ga0024b44eca99cb7135887c2aaf319d28

--
 Dr.-Ing. Christoph Hertzberg

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