Hey guys I am struggling with one equation right now, that I need for my bachelor thesis.

Let’s say I want to need the following equations

X_1 = y_1

X_2 = y_1+y_2

X_3 = y_1+y_2+y_3

…

How do I model this? I tried:

Equation(i)… X(i) =E= sum( i, y(i))

but this is apparently wrong because the set (of the sum) is under control already.

I also tried

Alias(i,j)

Equation(i)… X(i) =E= sum( (i =G= j) , y(i))

but that doesn’t work either.

Any suggestions would be much appreciated!

Thank you in advance!