How to define equality constraints? "Uncontrolled set entered as constant"

Dear all,

Very honored to join this helpful group.

May I ask how to define equality constraints on a certain set?

I wrote:

equ(i)… x(i)+y(i) =e= a(i) - b(i) ;

In this equation, I want express that for the set i, I have i equality constraints. x and y are decision variables; a and b are parameter, whose values are known.

But I got this error:“Uncontrolled set entered as constant”. I learnt that i cannot be used as the index number, yet still cannot figure out how to fix this.

Hope to hear from you soon. Thank you very much.

Cheers.


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Hi Tian

You have an error “uncontrolled set entered as constant”, but it is hard to see where this error originates, as you do not provide enough information (read the Guidelines to this forum).

Cheers

Renger



From: gamsworld@googlegroups.com [mailto:gamsworld@googlegroups.com] On Behalf Of Tian Zhang
Sent: Dienstag, 31. März 2015 05:17
To: gamsworld@googlegroups.com
Subject: How to define equality constraints? “Uncontrolled set entered as constant”



Dear all,



Very honored to join this helpful group.



May I ask how to define equality constraints on a certain set?



I wrote:



equ(i)… x(i)+y(i) =e= a(i) - b(i) ;



In this equation, I want express that for the set i, I have i equality constraints. x and y are decision variables; a and b are parameter, whose values are known.



But I got this error:“Uncontrolled set entered as constant”. I learnt that i cannot be used as the index number, yet still cannot figure out how to fix this.



Hope to hear from you soon. Thank you very much.



Cheers.


To unsubscribe from this group and stop receiving emails from it, send an email to gamsworld+unsubscribe@googlegroups.com.
To post to this group, send email to gamsworld@googlegroups.com.
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Hi Renger,

Thank you for the heads-up. I will rephrase my question here.

Basically, I have a set i, which has 48 elements. And I would like to define 48 equality constraints for each elements in my set i.

What I want to achieve is, for each i = 1:48, i have x(i)+y(i) =e= a(i) - b(i).

I expressed this as equ(i)… x(i)+y(i) =e= a(i) - b(i) ;

In this equation, x and y are decision variables (both have 48 numbers of variables); a and b are defined parameter.

Since GAMS does not recognize “i” as the index number, how can I represent those equation? I hope there will be other solutions, other than simply putting 48 equations there.


Thanks very much.

Regards,
Tian

On Tuesday, March 31, 2015 at 4:04:12 PM UTC+8, Renger van Nieuwkoop wrote:

Hi Tian

You have an error “uncontrolled set entered as constant”, but it is hard to see where this error originates, as you do not provide enough information (read the Guidelines to this forum).

Cheers

Renger



From: gams...@googlegroups.com [mailto:gams...@googlegroups.com] On Behalf Of Tian Zhang
Sent: Dienstag, 31. März 2015 05:17
To: gams...@googlegroups.com
Subject: How to define equality constraints? “Uncontrolled set entered as constant”



Dear all,



Very honored to join this helpful group.



May I ask how to define equality constraints on a certain set?



I wrote:



equ(i)… x(i)+y(i) =e= a(i) - b(i) ;



In this equation, I want express that for the set i, I have i equality constraints. x and y are decision variables; a and b are parameter, whose values are known.



But I got this error:“Uncontrolled set entered as constant”. I learnt that i cannot be used as the index number, yet still cannot figure out how to fix this.



Hope to hear from you soon. Thank you very much.



Cheers.


To unsubscribe from this group and stop receiving emails from it, send an email to gamsworld+...@googlegroups.com.
To post to this group, send email to gams...@googlegroups.com.
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Hi Tian

You probably haven’t defined the set (“set I /i1*i48/;”), but it is hard to tell, as you don’t give the complete code or an example that can reproduce the error. The equation itself looks fine.

Renger



From: gamsworld@googlegroups.com [mailto:gamsworld@googlegroups.com] On Behalf Of Tian Zhang
Sent: Mittwoch, 1. April 2015 07:53
To: gamsworld@googlegroups.com
Subject: Re: How to define equality constraints? “Uncontrolled set entered as constant”



Hi Renger,



Thank you for the heads-up. I will rephrase my question here.



Basically, I have a set i, which has 48 elements. And I would like to define 48 equality constraints for each elements in my set i.



What I want to achieve is, for each i = 1:48, i have x(i)+y(i) =e= a(i) - b(i).



I expressed this as equ(i)… x(i)+y(i) =e= a(i) - b(i) ;



In this equation, x and y are decision variables (both have 48 numbers of variables); a and b are defined parameter.



Since GAMS does not recognize “i” as the index number, how can I represent those equation? I hope there will be other solutions, other than simply putting 48 equations there.





Thanks very much.



Regards,

Tian

On Tuesday, March 31, 2015 at 4:04:12 PM UTC+8, Renger van Nieuwkoop wrote:

Hi Tian

You have an error “uncontrolled set entered as constant”, but it is hard to see where this error originates, as you do not provide enough information (read the Guidelines to this forum).

Cheers

Renger



From: gams...@googlegroups.com [mailto:gams...@googlegroups.com] On Behalf Of Tian Zhang
Sent: Dienstag, 31. März 2015 05:17
To: gams...@googlegroups.com
Subject: How to define equality constraints? “Uncontrolled set entered as constant”



Dear all,



Very honored to join this helpful group.



May I ask how to define equality constraints on a certain set?



I wrote:



equ(i)… x(i)+y(i) =e= a(i) - b(i) ;



In this equation, I want express that for the set i, I have i equality constraints. x and y are decision variables; a and b are parameter, whose values are known.



But I got this error:“Uncontrolled set entered as constant”. I learnt that i cannot be used as the index number, yet still cannot figure out how to fix this.



Hope to hear from you soon. Thank you very much.



Cheers.


To unsubscribe from this group and stop receiving emails from it, send an email to gamsworld+...@googlegroups.com.
To post to this group, send email to gams...@googlegroups.com.
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