Equation based on set number

Problems with syntax of GAMS
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sinagilassi
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Equation based on set number

Post by sinagilassi » 6 months ago

Hi,

I defined a set and a parameter as

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Sets i /1, 2/;   

Positive Variable X_V_ce(i);
 
one of the constraints is

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Z1(i).. X_V_ce(i) =e= X_V_ce(i+1) + ....

How it can be defined, i cannot be set i+1 !!

What can I do to add 1 or 2 to an element?

Regards

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Renger
Posts: 127
Joined: 1 year ago

Re: Equation based on set number

Post by Renger » 6 months ago

Hi
This is not a problem for Gams. For i = 2, it writes the equation as
Z1(i).. X_V_ce("2") =e= 0;
If you want another formulation for this case, you could use the cardinality of set i (the number of elements):
Z1(i).. X_V_ce(i) =e= X_V_ce(i+1)$(ord(i) ne card(i) + (.....)$(ord(i) eq card(i);
Hope this answers your question
Cheers
Renger

sinagilassi
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Posts: 8
Joined: 9 months ago

Re: Equation based on set number

Post by sinagilassi » 6 months ago

Hi Renger,

Thank you for your help
Renger wrote:
6 months ago
Hi
This is not a problem for Gams. For i = 2, it writes the equation as
Z1(i).. X_V_ce("2") =e= 0;
If you want another formulation for this case, you could use the cardinality of set i (the number of elements):
Z1(i).. X_V_ce(i) =e= X_V_ce(i+1)$(ord(i) ne card(i) + (.....)$(ord(i) eq card(i);
Hope this answers your question
Cheers
Renger

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