You keep talking in terms of implementations rather than the abstract object.
Here you say a square does not include information about its location but then you add the location in the class definition. In coordinate-free geometry, you have only three basic entities: scalars, points and vectors. You can use them to define all the standard geometric objects and write code purely in terms of these entities. Ed __________ Ed Angel Founding Director, Art, Research, Technology and Science Laboratory (ARTS Lab) Professor Emeritus of Computer Science, University of New Mexico 1017 Sierra Pinon Santa Fe, NM 87501 505-984-0136 (home) edward.an...@gmail.com 505-453-4944 (cell) http://www.cs.unm.edu/~angel > On Jul 23, 2020, at 4:09 PM, Frank Wimberly <wimber...@gmail.com> wrote: > > The mathematical concept of a point in R^2 is that a it is completely > determined by the values of its coordinates. Same coordinates, same point. > A square per se Is determined by the length of its side(s). There is no > information about it's location. > > If I were writing a Square class for a graphics application I would include > two member variables: > > LocationOfLowerLeft point; > LengthOfSide double; > > I haven't written code for years so beware. > > --- > Frank C. Wimberly > 140 Calle Ojo Feliz, > Santa Fe, NM 87505 > > 505 670-9918 > Santa Fe, NM > > On Thu, Jul 23, 2020, 3:58 PM uǝlƃ ↙↙↙ <geprope...@gmail.com > <mailto:geprope...@gmail.com>> wrote: > No, I don't. What's the difference? > > On 7/23/20 2:46 PM, Frank Wimberly wrote: > > OK. As long as you grok the difference between the mathematical concept > > and the OO concept. > > -- > ↙↙↙ uǝlƃ > > - .... . -..-. . -. -.. -..-. .. ... -..-. .... . .-. . > FRIAM Applied Complexity Group listserv > Zoom Fridays 9:30a-12p Mtn GMT-6 bit.ly/virtualfriam > <http://bit.ly/virtualfriam> > un/subscribe http://redfish.com/mailman/listinfo/friam_redfish.com > <http://redfish.com/mailman/listinfo/friam_redfish.com> > archives: http://friam.471366.n2.nabble.com/ > FRIAM-COMIC <http://friam.471366.n2.nabble.com/FRIAM-COMIC> > http://friam-comic.blogspot.com/ <http://friam-comic.blogspot.com/> > - .... . -..-. . -. -.. -..-. .. ... -..-. .... . .-. . > FRIAM Applied Complexity Group listserv > Zoom Fridays 9:30a-12p Mtn GMT-6 bit.ly/virtualfriam > un/subscribe http://redfish.com/mailman/listinfo/friam_redfish.com > archives: http://friam.471366.n2.nabble.com/ > FRIAM-COMIC http://friam-comic.blogspot.com/
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