Hello everyone, I hope you are well.

Could you help me by showing how I can have the inverse function of the incomplete regularized range here in Stan. I believe it is not implemented because I already checked at 3.13 Combinatorial Functions | Stan Functions Reference

Would the following code be correct ?

```
data {
real a; // Shape parameter
real x; // Probability value
}
parameters {
real<lower=0> lambda; // Inverse normalized lower incomplete gamma function result
}
model {
lambda ~ inv_gamma_p(a, x);
}
generated quantities {
real result = lambda; // Store the result in a variable
}
```

Edit: @maxbiostat edited this post for syntax highlighting