Hi everybody, i don"t know if it is the proper title for this subject but i have a question about equation.
I would like my X variable to be either equal to 4 or above a given value (ex: 4). such as:
Eq_constraint… X(A) > 0 then X(A) > 4 otherwise X(A) = 0
I basically have farms in my programm with a given area and a set of activities. for some activities if farmer decide to adopt these ativities they have to allocate directly a 4 ha area otherwise they cannot perform this activity.
I hope you have understood my question
thank you a lot in advance.
Pcho
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As i understood here x(A) is Area of the farm so you want to say if farmer select a task the minimum field area should be 4. Obviously it can be greater than so it think you need to use BIG M formulation like this HERE PAGE NUM 79 http://www.inf.ufpr.br/aurora/disciplinas/topicosia2/livros/search/integer.pdf
where BIGM is large value you can put the total area available for the whole farm, you need to introduce binary variable like y and then use this equations
x(A)-BIGM*y=4;
On Fri, Oct 4, 2013 at 1:57 AM, pcho wrote:
Hi everybody, i don"t know if it is the proper title for this subject but i have a question about equation.
I would like my X variable to be either equal to 4 or above a given value (ex: 4). such as:
Eq_constraint… X(A) > 0 then X(A) > 4 otherwise X(A) = 0
I basically have farms in my programm with a given area and a set of activities. for some activities if farmer decide to adopt these ativities they have to allocate directly a 4 ha area otherwise they cannot perform this activity.
I hope you have understood my question
thank you a lot in advance.
Pcho
Regards,
Owais Nooruddin
+358465700556
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Hi Pcho
You should look for “semicontinuous variables†on the GAMS web.
Regards
Arne
\
Arne Stolbjerg Drud
ARKI Consulting & Development A/S
Bagsvaerdvej 246A, DK-2880 Bagsvaerd, Denmark
Phone: (+45) 44 49 03 23, Fax: (+45) 44 49 03 33, email: adrud@arki.dk
From: gamsworld@googlegroups.com [mailto:gamsworld@googlegroups.com] On Behalf Of pcho
Sent: Friday, October 04, 2013 12:58 AM
To: gamsworld@googlegroups.com
Subject: equation with 2 conditions
Hi everybody, i don"t know if it is the proper title for this subject but i have a question about equation.
I would like my X variable to be either equal to 4 or above a given value (ex: 4). such as:
Eq_constraint… X(A) > 0 then X(A) > 4 otherwise X(A) = 0
I basically have farms in my programm with a given area and a set of activities. for some activities if farmer decide to adopt these ativities they have to allocate directly a 4 ha area otherwise they cannot perform this activity.
I hope you have understood my question
thank you a lot in advance.
Pcho
–
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