Dear all,

I am trying to solve an ODE at one time point T1 in future hence I feed a single value of solution time to the integrator by:

**real T1 = times[i];**

however I got data type error:

**Semantic error in ‘string’, line 48, column 9 to column 51:**

**Ill-typed arguments supplied to function ‘ode_rk45’. Expected arguments:**

**(real, vector) => vector, vector, real, real[]**

**Instead supplied arguments of incompatible type:**

**(real, vector, vector) => vector, vector, real, real, vector**

Then I tried to define an array of length 1 for solution time by this command:

**array[1] real T1 = times[i];**

but I failed to assign a real value to this array:

**Semantic error in ‘string’, line 47, column 4 to column 32:**

**Ill-typed arguments supplied to assignment operator =: lhs has type real[] and rhs has type real**

Here is my stan code:

```
functions{
vector PK3cmt(real t, vector states, vector theta){
real ka = theta[1];
real CL = theta[2];
real Vc = theta[3];
real Q = theta[4];
real Vp = theta[5];
real gut = states[1];
real cent = states[2];
real peri = states[3];
vector[3] dif;
dif[1] = - ka * gut;
dif[2] = -ka*gut - ((CL / Vc) + (Q / Vc))*cent + (Q * peri) / Vp;
dif[3] = (Q*cent)/ Vc - (Q*peri)/Vp;
return dif;
}
}
data{
int N;
//vector<lower = 0>[N] time;
array[N] real times;
int evid[N];
int cmt[N];
vector<lower = 0>[N] amt;
int nObs;
int iObs[nObs];
vector<lower=0>[N] cObs;
}
transformed data {
int nTheta = 5;
int nCmt = 3;
}
parameters{
vector[nTheta] theta; //{ka, CL, Vc, Q, Vp}
real<lower = 0> sigma;
}
transformed parameters{
vector[nCmt] U;
U[1] = 0;
U[2] = 0;
U[3] = 0;
array[N] vector[3] traj;
for(i in 1:N){
if (evid[i] == 1) U[cmt[i]] += amt[i];
else {
//real T1 = times[i]; // doesn't work
array[1] real T1 = times[i]; // also doesn't work
U = ode_rk45(PK3cmt, U, times[i-1], T1, theta);
traj[i] = U;
}
}
vector<lower=0>[N] concentrationHat = traj[][2] ./theta[3];
}
model{
theta[2] ~ lognormal(log(10), 0.25);
theta[4] ~ lognormal(log(15), 0.5);
theta[3] ~ lognormal(log(35), 0.25);
theta[5] ~ lognormal(log(105), 0.5);
theta[1] ~ lognormal(log(2.5), 1);
sigma ~ normal(0, 1);
cObs ~ lognormal(log(concentrationHat[iObs]), sigma);
}
```

Any help is apprecaited.

Hassan