diff --git a/src/bspline.rs b/src/bspline.rs
index 7c76f11..114fccb 100644
--- a/src/bspline.rs
+++ b/src/bspline.rs
@@ -22,6 +22,7 @@ fn in_shape(shape_f: &[f64], v: &[f64]) -> bool {
         .all(|(s, x)| (-0.5 <= *x) && (x <= s))
 }
 
+// TODO: sample nearby points
 #[derive(Debug, Serialize, Deserialize)]
 pub struct DefaultValue {
     #[serde(skip, default = "DefaultValue::make_rng")]
diff --git a/src/filter.rs b/src/filter.rs
index 3a6c253..591caf6 100644
--- a/src/filter.rs
+++ b/src/filter.rs
@@ -1,3 +1,6 @@
+//! Module containing gaussian smooth functions as well as helper functions to calculate ND fast
+//! fourier transforms
+
 use crate::error::Error;
 use itertools::Itertools;
 use ndarray::{Array, Array1, ArrayD, AsArray, Axis, Dimension, RemoveAxis, concatenate, s};