Re: Multiply and Divide operators for geometry types - Mailing list pgsql-general

From Alvaro Herrera
Subject Re: Multiply and Divide operators for geometry types
Date
Msg-id 20020411023630.002550a9.alvherre@atentus.com
Whole thread Raw
In response to Re: Multiply and Divide operators for geometry types  (Thomas Lockhart <lockhart@fourpalms.org>)
Responses Re: Multiply and Divide operators for geometry types  (Alvaro Herrera <alvherre@atentus.com>)
List pgsql-general
En Wed, 10 Apr 2002 17:56:02 -0700
Thomas Lockhart <lockhart@fourpalms.org> escribió:

> > Can any one explain what the * and / operators are supposed to do?
> > For example, what does it mean to multiply a box * a point?
>
> It is equivalent to a translation and a rotation. If you have worked
> with complex arithmetic, the analogy is with the real and complex axis,
> and the operations which can be done in those two dimensions.

There's something I don't quite understand here. If I do

SELECT box '((2,3),(4,5))' * point '(3,4)';
    ?column?
-----------------
 (-6,31),(-8,17)

But my complex aritmethic gives me

(-6,17),(-8,31)

As I read in your mail, each point in the box gets multiplied by the
other point, but this is not the case in the current code (CVS as of
earlier today... well, yesterday). Is this a bug, or am I understanding
something wrong?

--
Alvaro Herrera (<alvherre[a]atentus.com>)
"On the other flipper, one wrong move and we're Fatal Exceptions"
(T.U.X.: Term Unit X  - http://www.thelinuxreview.com/TUX/)

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