Please also provide the following information in addition to your question:

- Operating System: Win 10
- brms Version: 2.4.3

I’m trying to do a nonlinear regression involving the pnorm function. Seems brm does not like my using the pnorm function. I’m trying to test something out, which is why I don’t want to use logit, which I know will work. For simplicity, I’ve recreated probit regression as a nonlinear model:

x <- rnorm(1000)

p <- pnorm(x)

y <- rbinom(1000,prob=p,size=1)

brm.out <- brm(bf(y~pnorm(eta),eta~x,family=bernoulli(“identity”),nl=T),

data=dat,inits = “random”, chains = 1, iter = 1000, warmup = floor(1000/2),thin = 1,

prior=c(prior(normal(0,2.5),nlpar=“eta”)))

I get the following error:

SYNTAX ERROR, MESSAGE(S) FROM PARSER:

No matches for:

pnorm(real)

## Function pnorm not found.

error in ‘model34a443cc57c7_file34a4e3c531’ at line 23, column 30

```
21: for (n in 1:N) {
22: // compute non-linear predictor
23: mu[n] = pnorm(nlp_eta[n]);
^
24: }
```

Error in stanc(model_code = paste(program, collapse = “\n”), model_name = model_cppname, :

failed to parse Stan model ‘file34a4e3c531’ due to the above error.

Any ideas on how to code pnorm so brm will like it?