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MathGroup Archive 2004

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Re: Linear Programming

  • To: mathgroup at smc.vnet.net
  • Subject: [mg51011] Re: [mg50977] Linear Programming
  • From: DrBob <drbob at bigfoot.com>
  • Date: Fri, 1 Oct 2004 04:49:20 -0400 (EDT)
  • References: <200409300852.EAA26529@smc.vnet.net>
  • Reply-to: drbob at bigfoot.com
  • Sender: owner-wri-mathgroup at wolfram.com

This works, but it throws a meaningless error first:

NMinimize[{x + y, x >= 5, y >= 5,
    3*x >= 5*y, {x, y} \[Element] Integers},
   {x, y}]

\!\(\*
   RowBox[{\(NMinimize::"incst"\), \(\(:\)\(\ \)\), "\<\"\\!\\(NMinimize\\)
     was unable to generate any
       initial points satisfying the inequality constraints \
\\!\\({\\(\\(\\(\\(\\(\\(-3\\)\\)\\\\ \\(\\(Round[x]\\)\\)\\)\\) + \
\\(\\(5\\\\ \\(\\(Round[y]\\)\\)\\)\\)\\)\\) ? 0}\\). The initial region \
specified may not contain any feasible points. Changing the initial region or \
specifying explicit initial points may provide a better solution. \
\\!\\(\\*ButtonBox[\\\"More?\\\", ButtonStyle->\\\"RefGuideLinkText\\\", \
ButtonFrame->None, ButtonData:>\\\"NMinimize::incst\\\"]\\)\"\>"}]\)

{14., {x -> 9, y -> 5}}

Perhaps somebody out there can explain why this error message is "a good thing"?

Bobby

On Thu, 30 Sep 2004 04:52:32 -0400 (EDT), Rodrigo Malacarne <malacarne at gmail.com> wrote:

> Hi everybody,
>
> How can I insert a constraint in the following expression
>
> ConstrainedMin[x+y,{x>5,y>5,3x>5y},{x,y}]
>
> to find only integer results? Using the expression above I get
>
> {13.3333,{x->8.3333,y->5.}}
>
> but I want x to be an integer number.
>
> Cordially yours,
> Rodrigo
>
>
>
>



-- 
DrBob at bigfoot.com
www.eclecticdreams.net


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