Hello everyone,

I’m bigginer on GAMS, and i’m trying to use if for a modeling problem, nevertheless, i can’t make the true syntax for the following loop,

Can sameone help me doing it, thank you in advance,

Hello everyone,

I’m bigginer on GAMS, and i’m trying to use if for a modeling problem, nevertheless, i can’t make the true syntax for the following loop,

Can sameone help me doing it, thank you in advance,

Hi, do you need the loop to define a parameter or is it an equation?

No loops are used to define equations.

anyway, you don’t need a loop for this definition.

as a equation:

```
set
i /1*13/
;
alias(i,j,k)
eq(i).. log(gamma(i)) =e= - A*power(z(i),2) + 2*sum(j$(ord(j) ne ord(i)),m(j)*(B_0(i,j) + B_1(i,j)/(2*I)))
+ power(z(i),2)*sum((j,k)$(ord(j) ne ord(i) and ord(k) ne ord(i) and ord(j) ne ord(k)),m(j)*m(k)*B_1(j,k)/(4*power(I,2)));
```

as a parameter:

```
gamma(i) = exp(- A*power(z(i),2) + 2*sum(j$(ord(j) ne ord(i)),m(j)*(B_0(i,j) + B_1(i,j)/(2*I)))
+ power(z(i),2)*sum((j,k)$(ord(j) ne ord(i) and ord(k) ne ord(i) and ord(j) ne ord(k)),m(j)*m(k)*B_1(j,k)/(4*power(I,2))));
```

I think this is fine but, I suggest you check it.

bye

O thank you very much, I thaught that i had to use a loop,

I use your expression in in my code and it works very good,

Thank you again,