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我正在使用 Python 中的 Stan 跟踪示例代码，但由于语法错误，它没有被编译：

ValueError: Failed to parse Stan model 'anon_model_ad43313e8b4b0b001a1a5d32da64a34e'. Error message:
SYNTAX ERROR, MESSAGE(S) FROM PARSER:

variable "real" does not exist.
  error in 'unknown file name' at line 20, column 9
  -------------------------------------------------
    18: }
    19: model{
    20:     real l1;
                ^
    21:     real l2;   
  -------------------------------------------------

这是斯坦代码：

import numpy as np
import statsmodels.api as sm
import pystan
from scipy.stats import uniform, invgauss

stan_code = """
data{
    int<lower=0> N;
    vector[N] Y;
    vector[N] x1;
}
parameters{
    real beta0;
    real beta1;
    real<lower=0> lambda;
}
transformed parameters{
    vector[N] exb;
    vector[N] xb;

    for (i in 1:N) xb[i] = beta0 + beta1 * x1[i];
    for (i in 1:N) exb[i] = exp(xb[i]);
}
model{
    real l1;
    real l2;   
    vector[N] loglike;

    lambda ~ uniform(0.0001, 100);

    for (i in 1:N){
        l1 = 0.5 * (log(lambda) - log(2 * pi() * pow(Y[i], 3)));
        l2 = -lambda*pow(Y[i] - exb[i], 2)/(2 * pow(exb[i], 2) * Y[i]);
        loglike[i] = l1 + l2;
    }
    target += loglike;
}
"""

fit = pystan.stan(model_code=stan_code, data= stan_data, iter=5000, chains=3, warmup=2500, n_jobs=3)

有什么问题吗？我也在stan_data实现stan功能之前定义了。我阅读了关于模型块的 Stan 手册，它说允许在模型块中声明局部变量......请让我知道上面的问题。

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