> -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Behalf Of Reece Dunn > Sent: Thursday, May 22, 2003 6:54 AM > To: [EMAIL PROTECTED] > Subject: Re: [boost] proposal for efficient geom. vector class
> As for the point/vector/matrix from a non-graphics point-of-view, > I agree: > it should be applicable to any application that makes use of points, > vectors, etc. > > Regarding point = point +/- vector, a vector is a representation of a > distance (hence why it can be created via point - point), so the above > operations translate a point by a certain distance. Having point > = point +/- > point does not make sence, because a point is a *location* not a > *distance*. point = point +/- point might make sense. It depends upon the vector space you're using. In an affine space, you would be correct - you can't add points together. Well, even in that space, it can be useful from time to time: finding the midpoint [(p1+p2)/2] or some other barycentric combination. In a Grassman space, any point +/- point combination is a valid operation. The paper I referenced in my last e-mail provides a great discussion of this very point: http://portal.acm.org/citation.cfm?doid=504789.504792 -- Noah _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
