diff --git a/src/Schedulers.jl b/src/Schedulers.jl
index b78539b..1a1abe4 100644
--- a/src/Schedulers.jl
+++ b/src/Schedulers.jl
@@ -3,16 +3,14 @@ abstract type Scheduler end
 """
 Add noise to clean data using the forward diffusion process.
 
-cf. [[2006.11239] Denoising Diffusion Probabilistic Models](https://arxiv.org/abs/2006.11239) (Eq. 4)
-
 ## Input
   * `scheduler::Scheduler`: scheduler to use
-  * `clean_data::AbstractArray`: clean data to add noise to
-  * `noise::AbstractArray`: noise to add to clean data
-  * `timesteps::AbstractArray`: timesteps used to weight the noise
+  * `x₀::AbstractArray`: clean data to add noise to
+  * `ϵ::AbstractArray`: noise to add to clean data
+  * `t::AbstractArray`: timesteps used to weight the noise
 
 ## Output
-  * `noisy_data::AbstractArray`: noisy data at the given timesteps
+  * `xₜ::AbstractArray`: noisy data at the given timesteps
 """
 function add_noise(
   scheduler::Scheduler,
@@ -23,6 +21,8 @@ function add_noise(
   ⎷α̅ₜ = scheduler.⎷α̅[t]
   ⎷β̅ₜ = scheduler.⎷β̅[t]
 
+  # noisify clean data
+  # arxiv:2006.11239 Eq. 4
   xₜ = ⎷α̅ₜ' .* x₀ + ⎷β̅ₜ' .* ϵ
 
   return xₜ