fix: compile error

Author: dancixx

src/stochastic/autoregressive/agrach.rs

@@ -87,6 +87,7 @@ impl SamplingExt<f64> for AGARCH<f64> {
     x
   }
 
+  #[cfg(feature = "simd")]
   fn sample_simd(&self) -> Array1<f64> {
     use crate::stats::distr::normal::SimdNormal;
 
@@ -135,6 +136,60 @@ impl SamplingExt<f64> for AGARCH<f64> {
     x
   }
 
+  fn n(&self) -> usize {
+    #[cfg(not(feature = "simd"))]
+    self.n
+  }
+
+  #[cfg(feature = "simd")]
+  fn sample_simd(&self) -> Array1<f32> {
+    use crate::stats::distr::normal::SimdNormal;
+
+    let p = self.alpha.len();
+    let q = self.beta.len();
+
+    // Generate white noise
+    let z = Array1::random(self.n, SimdNormal::new(0.0, 1.0));
+
+    // Arrays for X_t and sigma_t^2
+    let mut x = Array1::<f32>::zeros(self.n);
+    let mut sigma2 = Array1::<f32>::zeros(self.n);
+
+    // Summation for unconditional variance init
+    let sum_alpha: f32 = self.alpha.iter().sum();
+    let sum_delta_half: f32 = self.delta.iter().sum::<f32>() * 0.5;
+    let sum_beta: f32 = self.beta.iter().sum();
+    let denom = (1.0 - sum_alpha - sum_delta_half - sum_beta).max(1e-8);
+
+    for t in 0..self.n {
+      if t == 0 {
+        sigma2[t] = self.omega / denom;
+      } else {
+        let mut var_t = self.omega;
+        // p-lag terms
+        for i in 1..=p {
+          if t >= i {
+            let x_lag = x[t - i];
+            let indicator = if x_lag < 0.0 { 1.0 } else { 0.0 };
+
+            var_t +=
+              self.alpha[i - 1] * x_lag.powi(2) + self.delta[i - 1] * x_lag.powi(2) * indicator;
+          }
+        }
+        // q-lag terms
+        for j in 1..=q {
+          if t >= j {
+            var_t += self.beta[j - 1] * sigma2[t - j];
+          }
+        }
+        sigma2[t] = var_t;
+      }
+      x[t] = sigma2[t].sqrt() * z[t];
+    }
+
+    x
+  }
+
   fn n(&self) -> usize {
     self.n
   }