I put a function `if_greater`

in the `functions`

block like this:

```
functions {
vector if_greater(vector x, vector y) {
int n;
vector[n] D;
n = rows(x);
for (i in 1:n){
D[i] = operator>(x[i],y[i]) ;
}
return D;
}
```

An error popped up and pointed to the `operator>`

function. I changed it to the conditional operator function ` x[i] > y[i] ? 1:0`

and it works!

I looked up the reference manual. the `operator`

function can be used in this way. So I wonder why the error occurred. Thanks.