Remove need to box kernel on model

src/fitter/recursive.rs

@@ -7,9 +7,9 @@ use crate::kernel::Kernel;
 
 use super::Fitter;
 
-pub struct Recursive {
+pub struct Recursive<K> {
     ts_new: Vec<f64>,
-    kernel: Box<dyn Kernel>,
+    kernel: K,
     ts: Vec<f64>,
     ms: Vec<f64>,
     vs: Vec<f64>,
@@ -28,8 +28,8 @@ pub struct Recursive {
     p_s: Vec<Array2<f64>>,
 }
 
-impl Recursive {
-    pub fn new(kernel: Box<dyn Kernel>) -> Self {
+impl<K: Kernel> Recursive<K> {
+    pub fn new(kernel: K) -> Self {
         let m = kernel.order();
         let h = kernel.measurement_vector();
 
@@ -56,7 +56,7 @@ impl Recursive {
     }
 }
 
-impl fmt::Debug for Recursive {
+impl<K: Kernel> fmt::Debug for Recursive<K> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("RecursiveFitter")
             .field("ts_new", &self.ts_new)
@@ -80,7 +80,7 @@ impl fmt::Debug for Recursive {
     }
 }
 
-impl Fitter for Recursive {
+impl<K: Kernel> Fitter for Recursive<K> {
     fn add_sample(&mut self, t: f64) -> usize {
         let idx = self.ts.len() + self.ts_new.len();