refer to an element of a two dimensional set

GAMS
1

Hi every body,

I have a code like the following:

set i/citieis/

alias(i,ii)

set OD(i,ii)
*

each element of OD is a pair of (origin,destination). I wonder how can I refer t the first element of a pair in a constriant. I know we can use ORD to refer to a specific element of a set but I want to refer to a n element inside an element of a set/

Thanks

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2

HI,

You can specifically refer to the elements by putting them in single quotation like (‘x’,’y’) given that ‘x’ and ‘y’ are elements of set i.



Yonas



From: gamsworld@googlegroups.com [mailto:gamsworld@googlegroups.com] On Behalf Of Fateme Fotuhi
Sent: 8. april 2014 03:42
To: gamsworld@googlegroups.com
Subject: refer to an element of a two dimensional set



Hi every body,



I have a code like the following:



*

set i/citieis/



alias(i,ii)



set OD(i,ii)




each element of OD is a pair of (origin,destination). I wonder how can I refer t the first element of a pair in a constriant. I know we can use ORD to refer to a specific element of a set but I want to refer to a n element inside an element of a set/



Thanks




\

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3

Thank you but my cities are not in text format, they are numbers and if I want to write a constriant over all OD pairs, I can not refer to the first element like this: ‘i’
it will give me an error

On Tuesday, April 8, 2014 6:30:29 AM UTC-4, Yonas Gebrekiros wrote:

HI,

You can specifically refer to the elements by putting them in single quotation like (‘x’,’y’) given that ‘x’ and ‘y’ are elements of set i.



Yonas



From: gams...@googlegroups.com [mailto:gams...@googlegroups.com] On Behalf Of Fateme Fotuhi
Sent: 8. april 2014 03:42
To: gams...@googlegroups.com
Subject: refer to an element of a two dimensional set



Hi every body,



I have a code like the following:



*

set i/citieis/



alias(i,ii)



set OD(i,ii)




each element of OD is a pair of (origin,destination). I wonder how can I refer t the first element of a pair in a constriant. I know we can use ORD to refer to a specific element of a set but I want to refer to a n element inside an element of a set/



Thanks




\

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–
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