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From Curtis Jensen <cur...@the-jensens.org>
Subject Re: [math] Cross and Dot Product (not centered at the origin)
Date Thu, 16 Jun 2011 19:43:08 GMT
On Wed, Jun 15, 2011 at 12:01 PM, Luc Maisonobe <Luc.Maisonobe@free.fr> wrote:
> Le 15/06/2011 19:57, Curtis Jensen a écrit :
>>
>> The Vector2D and Vector3D classes have dotProduct and crossProduct
>> methods.  I assume this is done be considering each vector originating
>
> There is no crossProduct in Vector2D in the current version I think.
>

You are correct.  It was sloppy typing on my part to include
crossProduct with Vector2D.

>> from the origin.  How can the dot product and cross products be
>> calculated for vectors not centered at the origin?
>
> Yes, these methods are intended for vectorial spaces, not affine spaces,
> which implies they work for vector centered at origin.
>
> We discussed on the dev list about having separate classes for
> Affine/Vectorial spaces and finally decided to merge everything in only one
> class per dimension. This is a classical choice and the user often already
> know what his instances represent.
>

What is the suggested way of getting the dot and cross products for
vectors not centered at the origin?  ie. the dot product of a corner
of a polygon.

Thanks,
Curtis

> Luc
>
>>
>> Thanks,
>> Curtis
>>
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