Hello all,

I want to programm a formulation: sum(t, sum(j∈N & j≠i, P(i,j,t))). The code is as follows:

```
set
i / 1,2,3 /
t / 1*24 /;
alias(i,j);
sum((t,j)$(t,j<>i), p(i,j,t))
```

However, the programm repor some errors:

148 Dimension different - The symbol is referenced with more/less indices as declared

Could someone can help me to correct it.

Thanks.

Li

Hi,

Your code snippet is obviously incomplete and if executed, it does not result in the error you describe.

- it does not declare p
- the sum() must be assigned to some other symbol
- the sum does not control i
- not sure what the t in the dollar condition is supposed to do
- j<>i is no valid GAMS syntax (if j and i are sets)

Maybe you want to do something like:

```
set i / 1,2,3 /
t / 1*24 /;
alias(i,j);
parameter p(i,j,t);
scalar x;
p(i,j,t) = uniformint(1,10);
x = sum((i,j,t)$(not sameas(i,j)), p(i,j,t));
display p,x;
```

I hope this helps!

Fred

Hi Fred,

Thank you for your prompt reply. It solves my problem perfectly.

Just as you said, I misinterpret the GAMS syntax 'j ≠i ’ as 'j<>i '.

Again, thank you!

Best,

Li