RE: [Help-glpk] abs

[Meketon, Marc]

Typically you define two non-negative variables, say rPlus and rNegative whose difference is (1-y) and [with the correct objective function] whose sum is the absolute value of (1-y).

 

The code is something like:

 

var rPlus >=0;

var rNegative >=0;

 

maximize obj - (rPlus + rNegative);

 

subject to AbsoluteValueTypeConstraint

  1-y = rPlus - rNegative;

 

Note that rPlus+rNegative is the absolute value of (1-y) when that sum is minimized.

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From: help-glpk-bounces+address@hidden [mailto:help-glpk-bounces+address@hidden On Behalf Of name name
Sent: Saturday, November 20, 2010 7:29 AM
To: address@hidden
Subject: [Help-glpk] abs

Hello,

I want to calculate

 

var y,>=0;

 

maximize obj:

abs(1-y);

 

fa:

...

fb:

...

 

solve;

...

data;

...

I get the argument for abs has invalide type, could you tell me how I could do this?

 

Is it possible to solve the maximization probleme several times?

 

something like this

 

 

var y,>=0;

{k in 1 .. 20} :

/* To get the solution for k=1, solution for k=2 ...*/

maximize obj:

abs(1-y);

 

fa:

...

fb:

...

 

solve;

...

data;

...

 

And the last question

How can I compile an model model.mod where the data is in a file model.dat

 

Thank you a lot

Onor

 

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