how to code this ?

Hi

Just use Y(i-1,r,t). Note however, that this means that you can’t use this for the first i if there is no value for i-1. If it is a variable, you probably will have to fix the Y(i-1) to a certain value or you can define the equation for all i > 1

```
myeq(i,r)$(ord(i)>1)...
Y(i,r,t) =L= sum(t, Y(i-1,r,t);
```

Cheers

Renger

THANK YOU