Added delta and more tests.

src/factor_graph.rs

@@ -49,13 +49,29 @@ impl Variable {
         self.factors.insert(factor, Gaussian::from_pi_tau(0.0, 0.0));
     }
 
-    pub fn update_value(&mut self, factor: usize, value: Gaussian) {
+    pub fn update_value(&mut self, factor: usize, value: Gaussian) -> f64 {
         let old = self.factors[&factor];
 
         self.factors.insert(factor, value * old / self.value);
+
+        let pi_delta = (self.value.pi() - value.pi()).abs();
+
+        let delta = if !pi_delta.is_finite() {
+            0.0
+        } else {
+            let pi_delta = pi_delta.sqrt();
+            let tau_delta = (self.value.tau() - value.tau()).abs();
+
+            if pi_delta > tau_delta {
+                pi_delta
+            } else {
+                tau_delta
+            }
+        };
+
         self.value = value;
 
-        // debug!("Variable::value value={:?}", self.value);
+        delta
     }
 
     pub fn get_value(&self) -> Gaussian {
@@ -67,8 +83,6 @@ impl Variable {
 
         self.factors.insert(factor, message);
         self.value = self.value / old * message;
-
-        // debug!("Variable::message value={:?}", self.value);
     }
 
     pub fn get_message(&self, factor: usize) -> Gaussian {
@@ -344,7 +358,7 @@ impl TruncateFactor {
         }
     }
 
-    pub fn update(&self, variable_arena: &mut VariableArena) {
+    pub fn update(&self, variable_arena: &mut VariableArena) -> f64 {
         let (x, fx) = variable_arena
             .get(self.variable)
             .map(|variable| (variable.get_value(), variable.get_message(self.id)))
@@ -376,6 +390,6 @@ impl TruncateFactor {
         variable_arena
             .get_mut(self.variable)
             .unwrap()
-            .update_value(self.id, gaussian);
+            .update_value(self.id, gaussian)
     }
 }