[FRIAM] square land math question

[Angel Edward]

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.angel at gmail.com
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> On Jul 23, 2020, at 4:09 PM, Frank Wimberly <wimberly3 at 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 ↙↙↙ <gepropella at gmail.com <mailto:gepropella at 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
> 
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