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st: Why the square of a negative number is still negative


From   "Tiago V. Pereira" <tiago.pereira@mbe.bio.br>
To   statalist@hsphsun2.harvard.edu
Subject   st: Why the square of a negative number is still negative
Date   Fri, 16 Dec 2011 14:49:27 -0200 (BRST)

Thank yo very much, Austin and João Ricardo, for your extremely useful
explanations.

Tiago

----------------------------------------


Dear statalisters,

Can someone explain why is this happening?:

local x = -2
*/Approach A:
dis (`x'^2)*(5)
*/Approach B:
dis (`x'*`x')*(5)
*/Approach C:
 dis ((`x')^2)*(5)


My output is:

. dis (`x'^2)*(5)
-20

. */Approach B:

. dis (`x'*`x')*(5)
20

. */Approach C:

.  dis ((`x')^2)*(5)
20


Do I need vacations? (Am I forgetting something very simple from
mathematics?)

All the best,

Tiago




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