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MathGroup Archive 2008

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weird NMaximize behaviour

  • To: mathgroup at smc.vnet.net
  • Subject: [mg92049] weird NMaximize behaviour
  • From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
  • Date: Thu, 18 Sep 2008 06:15:53 -0400 (EDT)

I have just encountered strange behaviour by NMaximize (which has been  
ruining a demonstration I have been working on):

This is fine:

NMaximize[{(x - 1)^2, -2 <= x <= 2}, {x}]
{9., {x -> -2.}}

but this definitely is not:

NMaximize[{(x - 1)^2, -2 <= x <= 2 && -1 <= y <= 1}, {x, y}]
{1., {x -> 2., y -> 0.87904}}

The objective function s independent of y, yet NMaximize seems to go  
off on some wild goose chase and ends up with a very poor "maximum".

This does not happen here:

NMaximize[{(x - 2)^2, -2 <= x <= 2}, {x}]
{16., {x -> -2.}}

NMaximize[{(x - 2)^2, -2 <= x <= 2 && -1 <= y <= 1}, {x, y}]
{16., {x -> -2., y -> -0.980305}}

Kind of weird.

Andrzej Kozlowski


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