[FRIAM] square land math question

[Frank Wimberly]

That's because I was trying to illustrate the
difference between the abstract mathematical definition and an
implementation suitable for computer graphics.  I had just asked Glen if he
grokked the difference and he said no.
---
Frank C. Wimberly
140 Calle Ojo Feliz,
Santa Fe, NM 87505

505 670-9918
Santa Fe, NM

On Thu, Jul 23, 2020, 4:27 PM Angel Edward <edward.angel at gmail.com> wrote:

> 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
> 505-453-4944 (cell)  http://www.cs.unm.edu/~angel
>
> 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> 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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