out of range parameter

Archiver · December 12, 2013, 11:40am

Hello everyone !

I want to substract two consecutive values of a parameter and I am worried about the sets…
Here is my problem :

P(t) is defined over t from 1 to 10

Then I define R(t)=P(t)-P(t-1)

What is the value of R(‘1’) ? Can I be sure that it is P(‘1’) ?
ideally I would like to have R(‘1’)=0…

Thx for your help !

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Archiver · December 12, 2013, 11:49am

Hello Jacques,

I think you should try the following:

*Here you ensure that R(‘1’)=0
EQ1(t)$(ORD(t)=1)… R(t)=e=0;

*Here you compute R(t) for t>1
EQ2(t)$(ORD(t) gt 1)… R(t)=P(t)-P(t-1);

Hope that helps,

Konstantinos Petridis

Î¤Î· Î ÎÎ¼Ï€Ï„Î·, 12 Î”ÎµÎºÎµÎ¼Î²ÏÎ¯Î¿Ï… 2013 12:40:10 Î¼.Î¼. UTC+2, Î¿ Ï‡ÏÎ®ÏƒÏ„Î·Ï‚ Jacques ÎÎ³ÏÎ±ÏˆÎµ:

Hello everyone !

I want to substract two consecutive values of a parameter and I am worried about the sets…
Here is my problem :

P(t) is defined over t from 1 to 10

Then I define R(t)=P(t)-P(t-1)

What is the value of R(‘1’) ? Can I be sure that it is P(‘1’) ?
ideally I would like to have R(‘1’)=0…

Thx for your help !

–
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Archiver · December 12, 2013, 12:02pm

Thank you Constantinos,
This works, but I would like to be sure that it is necessary, in order to optimize the code.
What would be the value of R(t)=P(t)-P(t-1) for t=1, if I do not define P(‘1’) specifically ?
P(t-1) is “out of range”, so how does GAMS handle it ?

Thx,
Jacques

Le jeudi 12 dÃ©cembre 2013 11:49:06 UTC+1, ÎšÏ‰Î½ÏƒÏ„Î±Î½Ï„Î¯Î½Î¿Ï‚ Î ÎµÏ„ÏÎ¯Î´Î·Ï‚ a Ã©crit :

Hello Jacques,

I think you should try the following:

*Here you ensure that R(‘1’)=0
EQ1(t)$(ORD(t)=1)… R(t)=e=0;

*Here you compute R(t) for t>1
EQ2(t)$(ORD(t) gt 1)… R(t)=P(t)-P(t-1);

Hope that helps,

Konstantinos Petridis

Î¤Î· Î ÎÎ¼Ï€Ï„Î·, 12 Î”ÎµÎºÎµÎ¼Î²ÏÎ¯Î¿Ï… 2013 12:40:10 Î¼.Î¼. UTC+2, Î¿ Ï‡ÏÎ®ÏƒÏ„Î·Ï‚ Jacques ÎÎ³ÏÎ±ÏˆÎµ:

Hello everyone !

I want to substract two consecutive values of a parameter and I am worried about the sets…
Here is my problem :

P(t) is defined over t from 1 to 10

Then I define R(t)=P(t)-P(t-1)

What is the value of R(‘1’) ? Can I be sure that it is P(‘1’) ?
ideally I would like to have R(‘1’)=0…

Thx for your help !

–
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Archiver · December 12, 2013, 12:17pm

Hi,

At t=1, the value of R(t) will be equal to P(t). The value of P(â€˜0â€™) by default is zero.

Yonas

From: gamsworld@googlegroups.com [mailto:gamsworld@googlegroups.com] On Behalf Of Jacques
Sent: 12. desember 2013 12:02
To: gamsworld@googlegroups.com
Subject: Re: out of range parameter

Thank you Constantinos,
This works, but I would like to be sure that it is necessary, in order to optimize the code.
What would be the value of R(t)=P(t)-P(t-1) for t=1, if I do not define P(‘1’) specifically ?
P(t-1) is “out of range”, so how does GAMS handle it ?

Thx,
Jacques

Le jeudi 12 dÃ©cembre 2013 11:49:06 UTC+1, ÎšÏ‰Î½ÏƒÏ„Î±Î½Ï„Î¯Î½Î¿Ï‚ Î ÎµÏ„ÏÎ¯Î´Î·Ï‚ a Ã©crit :

Hello Jacques,

I think you should try the following:

*Here you ensure that R(‘1’)=0
EQ1(t)$(ORD(t)=1)… R(t)=e=0;

*Here you compute R(t) for t>1
EQ2(t)$(ORD(t) gt 1)… R(t)=P(t)-P(t-1);

Hope that helps,

Konstantinos Petridis

Î¤Î· Î ÎÎ¼Ï€Ï„Î·, 12 Î”ÎµÎºÎµÎ¼Î²ÏÎ¯Î¿Ï… 2013 12:40:10 Î¼.Î¼. UTC+2, Î¿ Ï‡ÏÎ®ÏƒÏ„Î·Ï‚ Jacques ÎÎ³ÏÎ±ÏˆÎµ:

Hello everyone !

I want to substract two consecutive values of a parameter and I am worried about the sets…
Here is my problem :

P(t) is defined over t from 1 to 10

Then I define R(t)=P(t)-P(t-1)

What is the value of R(‘1’) ? Can I be sure that it is P(‘1’) ?
ideally I would like to have R(‘1’)=0…

Thx for your help !

–
To unsubscribe from this group and stop receiving emails from it, send an email to gamsworld+unsubscribe@googlegroups.com.
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Archiver · December 12, 2013, 12:17pm

Dear Jacques,

I did the following in order to understand how GAMS handles this structure that you ask.

set t /1*10/;

parameter P(t), R(t),d;
P(t)=uniform(0,1);

R(t)=P(t)-P(t-1);
d=R(‘1’);
display d, R, P;

From the results you can see that R(1)=P(1) because there is no 0 label (e.g. P(0)).

Hope that helped,

Konstantinos Petridis

Î¤Î· Î ÎÎ¼Ï€Ï„Î·, 12 Î”ÎµÎºÎµÎ¼Î²ÏÎ¯Î¿Ï… 2013 1:02:05 Î¼.Î¼. UTC+2, Î¿ Ï‡ÏÎ®ÏƒÏ„Î·Ï‚ Jacques ÎÎ³ÏÎ±ÏˆÎµ:

Thank you Constantinos,
This works, but I would like to be sure that it is necessary, in order to optimize the code.
What would be the value of R(t)=P(t)-P(t-1) for t=1, if I do not define P(‘1’) specifically ?
P(t-1) is “out of range”, so how does GAMS handle it ?

Thx,
Jacques

Le jeudi 12 dÃ©cembre 2013 11:49:06 UTC+1, ÎšÏ‰Î½ÏƒÏ„Î±Î½Ï„Î¯Î½Î¿Ï‚ Î ÎµÏ„ÏÎ¯Î´Î·Ï‚ a Ã©crit :

Hello Jacques,

I think you should try the following:

*Here you ensure that R(‘1’)=0
EQ1(t)$(ORD(t)=1)… R(t)=e=0;

*Here you compute R(t) for t>1
EQ2(t)$(ORD(t) gt 1)… R(t)=P(t)-P(t-1);

Hope that helps,

Konstantinos Petridis

Î¤Î· Î ÎÎ¼Ï€Ï„Î·, 12 Î”ÎµÎºÎµÎ¼Î²ÏÎ¯Î¿Ï… 2013 12:40:10 Î¼.Î¼. UTC+2, Î¿ Ï‡ÏÎ®ÏƒÏ„Î·Ï‚ Jacques ÎÎ³ÏÎ±ÏˆÎµ:

Hello everyone !

I want to substract two consecutive values of a parameter and I am worried about the sets…
Here is my problem :

P(t) is defined over t from 1 to 10

Then I define R(t)=P(t)-P(t-1)

What is the value of R(‘1’) ? Can I be sure that it is P(‘1’) ?
ideally I would like to have R(‘1’)=0…

Thx for your help !

–
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Archiver · December 12, 2013, 12:20pm

For example, is it possible to fix “R.l(‘1’)=0;” in the parameter section, and avoid your first equation ?

Thank you Constantinos,
This works, but I would like to be sure that it is necessary, in order to optimize the code.
What would be the value of R(t)=P(t)-P(t-1) for t=1, if I do not define P(‘1’) specifically ?
P(t-1) is “out of range”, so how does GAMS handle it ?

Thx,
Jacques

Hello Jacques,

I think you should try the following:

*Here you ensure that R(‘1’)=0
EQ1(t)$(ORD(t)=1)… R(t)=e=0;

*Here you compute R(t) for t>1
EQ2(t)$(ORD(t) gt 1)… R(t)=P(t)-P(t-1);

Hope that helps,

Konstantinos Petridis

Î¤Î· Î ÎÎ¼Ï€Ï„Î·, 12 Î”ÎµÎºÎµÎ¼Î²ÏÎ¯Î¿Ï… 2013 12:40:10 Î¼.Î¼. UTC+2, Î¿ Ï‡ÏÎ®ÏƒÏ„Î·Ï‚ Jacques ÎÎ³ÏÎ±ÏˆÎµ:

Hello everyone !

I want to substract two consecutive values of a parameter and I am worried about the sets…
Here is my problem :

P(t) is defined over t from 1 to 10

Then I define R(t)=P(t)-P(t-1)

What is the value of R(‘1’) ? Can I be sure that it is P(‘1’) ?
ideally I would like to have R(‘1’)=0…

Thx for your help !

–
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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Archiver · December 12, 2013, 1:33pm

Jacques, you have already been answered, but two things:

To fix a variable, you would use R.fx(‘1’)=0 not .l, that sets the
value for the solver’s first iteration.
Fixing variables should be done at least after the variable has
been declared, so be wary if you’re putting it in a parameter section.

Regards and good luck !!
Claudio

On Thu, Dec 12, 2013 at 8:20 AM, Jacques wrote:

For example, is it possible to fix “R.l(‘1’)=0;” in the parameter section,
and avoid your first equation ?

Le jeudi 12 dÃ©cembre 2013 12:02:05 UTC+1, Jacques a Ã©crit :

Thank you Constantinos,
This works, but I would like to be sure that it is necessary, in order to
optimize the code.
What would be the value of R(t)=P(t)-P(t-1) for t=1, if I do not define
P(‘1’) specifically ?
P(t-1) is “out of range”, so how does GAMS handle it ?

Thx,
Jacques

Le jeudi 12 dÃ©cembre 2013 11:49:06 UTC+1, ÎšÏ‰Î½ÏƒÏ„Î±Î½Ï„Î¯Î½Î¿Ï‚ Î ÎµÏ„ÏÎ¯Î´Î·Ï‚ a Ã©crit :

Hello Jacques,

I think you should try the following:

*Here you ensure that R(‘1’)=0
EQ1(t)$(ORD(t)=1)… R(t)=e=0;

*Here you compute R(t) for t>1
EQ2(t)$(ORD(t) gt 1)… R(t)=P(t)-P(t-1);

Hope that helps,

Konstantinos Petridis

Î¤Î· Î ÎÎ¼Ï€Ï„Î·, 12 Î”ÎµÎºÎµÎ¼Î²ÏÎ¯Î¿Ï… 2013 12:40:10 Î¼.Î¼. UTC+2, Î¿ Ï‡ÏÎ®ÏƒÏ„Î·Ï‚ Jacques
ÎÎ³ÏÎ±ÏˆÎµ:

Hello everyone !

I want to substract two consecutive values of a parameter and I am
worried about the sets…
Here is my problem :

P(t) is defined over t from 1 to 10

Then I define R(t)=P(t)-P(t-1)

What is the value of R(‘1’) ? Can I be sure that it is P(‘1’) ?
ideally I would like to have R(‘1’)=0…

Thx for your help !

–
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