fix alphas_cumprod

src/diffusers/schedulers/scheduling_ddpm.py

@@ -137,8 +137,8 @@ class DDPMScheduler(SchedulerMixin, ConfigMixin):
         return pred_prev_sample
 
     def forward_step(self, original_sample, noise, t):
-        sqrt_alpha_prod = self.alpha_prod_t[t] ** 0.5
-        sqrt_one_minus_alpha_prod = (1 - self.alpha_prod_t[t]) ** 0.5
+        sqrt_alpha_prod = self.alphas_cumprod[t] ** 0.5
+        sqrt_one_minus_alpha_prod = (1 - self.alphas_cumprod[t]) ** 0.5
         noisy_sample = sqrt_alpha_prod * original_sample + sqrt_one_minus_alpha_prod * noise
         return noisy_sample