Summation over same set

GAMS
1

Hi,

i have a system with set i, which is p1, p2, p3

now I have a table

table G_coeff(i,i)

p1 p2 p3
p1 0.1 0.3 0.8
p2 0.2 0.5 0.6
p3 0.1 0.5 0.8

v(i), theta(i) is variable.

I need to sum over all (i,i) combination. that is as follows,


powerloss … sum ((i,i), G_coeff(i,i)(v(i)**2+v(i)**2-2v(i)*v(i)*cos(theta(i))))

but it said statement already under control.

Can anyone help?





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2

Hi Ahmed
Define the set i with multiple nnames:
Set I/P1*P3/
Alias(I,I2);
table G_coeff(i,i)

p1 p2 p3
p1 0.1 0.3 0.8
p2 0.2 0.5 0.6
p3 0.1 0.5 0.8

Variable V(I),Theta(I);

Now sue “Sum((I,I2),…)” instead of “Sum((I,I),…)”
I Hope this will be useful.

On Wed, Oct 10, 2012 at 2:27 AM, Syed Sabbir Ahmed wrote:

Hi,

i have a system with set i, which is p1, p2, p3

now I have a table

table G_coeff(i,i)

p1 p2 p3
p1 0.1 0.3 0.8
p2 0.2 0.5 0.6
p3 0.1 0.5 0.8

v(i), theta(i) is variable.

I need to sum over all (i,i) combination. that is as follows,


powerloss … sum ((i,i), G_coeff(i,i)(v(i)**2+v(i)**2-2v(i)*v(i)*cos(theta(i))))

but it said statement already under control.

Can anyone help?





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3

Dear Syed



If you use coeff(i,i) in an expression, Gams only takes the diagonal elements (In the declaration part, GAMS doesn’t make that distinction), therefore introduce an alias:



alias(i,j);



coeff(I,j) stands now for all the elements.



Now you can adjust your equation accordingly by summing over (I,j) and not (I,i).



Cheers



Renger









From: gamsworld@googlegroups.com [mailto:gamsworld@googlegroups.com] On Behalf Of Syed Sabbir Ahmed
Sent: Wednesday, October 10, 2012 12:58 AM
To: gamsworld@googlegroups.com
Subject: Summation over same set



Hi,



i have a system with set i, which is p1, p2, p3



now I have a table



table G_coeff(i,i)



p1 p2 p3

p1 0.1 0.3 0.8

p2 0.2 0.5 0.6

p3 0.1 0.5 0.8



v(i), theta(i) is variable.



I need to sum over all (i,i) combination. that is as follows,





powerloss … sum ((i,i), G_coeff(i,i)(v(i)**2+v(i)**2-2v(i)*v(i)*cos(theta(i))))



but it said statement already under control.



Can anyone help?












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