fix: SVS: post-review changes

src/svm/svc.rs

@@ -462,13 +462,7 @@ impl<'a, T: RealNumber, M: Matrix<T>, K: Kernel<T, M::RowVector>> Optimizer<'a,
         range
     }
 
-    fn smo(
-        &mut self,
-        idx_1: Option<usize>,
-        idx_2: Option<usize>,
-        tol: T,
-        cache: &mut Cache<T, M, K>,
-    ) -> bool {
+    fn select_pair(&mut self, idx_1: Option<usize>, idx_2: Option<usize>, cache: &mut Cache<T, M, K>) -> Option<(usize, usize, T)> {
         let mut idx_1 = idx_1;
         let mut idx_2 = idx_2;
 
@@ -535,8 +529,8 @@ impl<'a, T: RealNumber, M: Matrix<T>, K: Kernel<T, M::RowVector>> Optimizer<'a,
         }        
 
         if idx_1.is_none() || idx_2.is_none() {
-            return false;
-        }
+            None
+        } else {
 
             let idx_1 = idx_1.unwrap();
             let idx_2 = idx_2.unwrap();
@@ -545,8 +539,20 @@ impl<'a, T: RealNumber, M: Matrix<T>, K: Kernel<T, M::RowVector>> Optimizer<'a,
                 k_v_12 = Some(self.kernel.apply(&self.sv[idx_1].x, &self.sv[idx_2].x));
             }
 
-        let k_v_12 = k_v_12.unwrap();
+            Some((idx_1, idx_2, k_v_12.unwrap()))
+        }
+    }
 
+    fn smo(
+        &mut self,
+        idx_1: Option<usize>,
+        idx_2: Option<usize>,
+        tol: T,
+        cache: &mut Cache<T, M, K>,
+    ) -> bool {
+        
+        match self.select_pair(idx_1, idx_2, cache) {
+            Some((idx_1, idx_2, k_v_12)) => {
                 let mut curv = self.sv[idx_1].k + self.sv[idx_2].k - T::two() * k_v_12;
                 if curv <= T::zero() {
                     curv = self.tau;
@@ -577,6 +583,10 @@ impl<'a, T: RealNumber, M: Matrix<T>, K: Kernel<T, M::RowVector>> Optimizer<'a,
                 self.update(idx_1, idx_2, step, cache);
 
                 return self.gmax - self.gmin > tol;
+            },
+            None => false
+        }        
+        
     }
 
     fn update(&mut self, v1: usize, v2: usize, step: T, cache: &mut Cache<T, M, K>) {