Hi ,

My stan code looks like this. I have defined the parameters in matrix form .

```
data {
int<lower=1> N;
int<lower=1> N1;
int<lower=1> N2;
int<lower=1> N11;
int<lower=1> w;
int<lower=0,upper=1> y[N];
int<lower=1> K1;
matrix[N,K1] x11;
//matrix[N2,K1] x2;
}
parameters {
vector[w] alpha1;
matrix[K1,w] beta1;
vector <lower=0> [w] lambda;
}
model {
vector[N] mu1;
for(i in 1:N1){
mu1[i] = alpha1[1]+ x11[i,] * beta1[,1];
}
for(i in N11:N){
mu1[i] = alpha1[2]+ x11[i,] * beta1[,2];
}
//priors
for(k in 1:w){
target +=normal_lpdf(beta1[,k]| 0,1/lambda[k]);
target +=normal_lpdf(alpha1[k]| 0,10);
}
target += cauchy_lpdf(lambda[1]|0,1);
target += cauchy_lpdf(lambda[2]|0,1);
for(i in 1:N1){
target += bernoulli_logit_lpmf(y[i] | mu1[i]);
}
for(i in N11:N){
target += bernoulli_logit_lpmf(y[i] | mu1[i]);
}
}
****
However I got this error:
![image|690x47](upload://305OzQHNb0Q0OO0G9S2cJNjoQf7.png)
I double checked the code but I have defined the variable "x11" in the code. I keep getting this error.
Can anyone help me to fix this?
```