diff -r efa60bc4f743 -r b087e3eab191 src/fourier.rs
--- a/src/fourier.rs	Thu Aug 29 00:00:00 2024 -0500
+++ b/src/fourier.rs	Tue Dec 31 09:25:45 2024 -0500
@@ -3,14 +3,14 @@
 */
 
 use alg_tools::types::{Num, Float};
-use alg_tools::mapping::{RealMapping, Mapping};
+use alg_tools::mapping::{RealMapping, Mapping, Space};
 use alg_tools::bisection_tree::Weighted;
 use alg_tools::loc::Loc;
 
 /// Trait for Fourier transforms. When F is a non-complex number, the transform
 /// also has to be non-complex, i.e., the function itself symmetric.
 pub trait Fourier<F : Num> : Mapping<Self::Domain, Codomain=F> {
-    type Domain;
+    type Domain : Space;
     type Transformed : Mapping<Self::Domain, Codomain=F>;
 
     fn fourier(&self) -> Self::Transformed;